# Nemett Jaguar--Canadian style



## Brian Rupnow (May 11, 2014)

I have spent the last week looking at model engine plans. The Nemett Lynx is all the rage right now, and I will be following all of the builds that are currently happening. However, as nice as it is, I prefer to see a lot of the moving parts in action,i.e. pushrods, rocker arms, etcetera. The one thing I don't like about the six internal combustion engines I have built so far, is that they all have open crankcases, and they sling oil all over the place. I know that quite a few have built the two cylinder Nemett Bobcat. The Jaguar is basically the Bobcat with one cylinder lopped off. It has exposed pushrods and rocker arms, but the crankcase and timing gears themselves are totally enclosed. It appears to have "splash lubrication" for the rod and the main crankshaft bearings. I have a copy of Malcom Strides original metric drawings, and I an going through them and modelling them in 3D solidworks, from which I will create my own detail drawings in British Imperial "inch" dimensions. I have already found mistakes in the drawings, so it definitely pays to model everything first. After I get the modeling finished, then I will step away, have a good look at what I have done, and then make changes which make sense to me. There will definitely be changes, and yet, by and large it will still be Malcom Stride's engine---with a Canadian touch.---Brian


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## Brian Rupnow (May 11, 2014)

Well there!!!---That's enough silliness for one day. I have modelled 13 parts and one assembly since 6:30 this morning. It's a nice day outside, time to get out my 1931 Ford roadster and go for a little tour.


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## Brian Rupnow (May 11, 2014)

Now I need help from anybody who has built this engine or the Bobcat. (They have the same cylinders and heads). The drawing of the cylinder head which I have has a fold right in the center of the drawing, and I can't make out the diameter of the large counterbore on the cylinder side of the head, and I can't tell the depth and diameter of the shallow counterbores for the valve guides.---I don't have a clear dimension of the cylinder i.d. either, only I assume it is 24mm, same as the o.d. of the cylinder liner.---Brian


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## Jasonb (May 11, 2014)

Replied on the other side.

J


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## Brian Rupnow (May 11, 2014)

Well, I got my question answered and kept on modeling. This is a section view of the current state. I don't have any bearings in yet, and I'm not sure about the location of the flywheel, as I haven't modeled the tapered bushing that locates it yet. I am quite surprised at the number on mistakes I am finding as I work my way through this. I am certainly glad that I just didn't accept the drawings as being correct and start machining. I couldn't understand why the cylinder has a liner in it. Now I see---it shows up in the section view. At bottom dead center the piston skirt extends below the cylinder by quite a bit. There is an assortment of ways to get around this, but so far I am modeling exactly as per the drawings, (except for mistakes that I keep finding and correcting).


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## BronxFigs (May 11, 2014)

Brian-

Another example of perfection.  Thanks for sharing your concepts, for proving the design, and for correcting the mistakes.  Can't wait for the metal version.

Frank


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## Jasonb (May 12, 2014)

Brian, I have listed quite a few errors in your rendering over on the other site. To be fair to Malcom I see more errors on your drawing so far than I do on his plans.


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## gus (May 12, 2014)

The Nemett Epidemic or craze coming. Best to take cover.th_wav

The Nemett Virus must have mutated into Lynx,Bobcat,Jaguar etc etc. Will be fun watching following HMEM members building their version of  Nemetts.th_wav


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## gus (May 12, 2014)

OK. Gus just got infected too. Will build a Jaguar too but will be 2015. Geared cam drive and push rods. 

Brian, When can see your Canadian Nemett-Jaguar going.


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## Brian Rupnow (May 12, 2014)

Okay--a few admissions to make. I read through the 42 pages of build notes last night (which, by the way are excellently done) and realized that #1--I have the sump bolted on upside down. #2--their is a different bolt circle in the bottom of the cylinder as opposed to the bolt pattern in the top. #3--Something is said about the rocker arms being right and left hand which I had completely missed. Once I take all that into consideration, there are far fewer mistakes in the drawings than I originally alluded to. The drawings I have all appear to have been scanned by folding in the center to get them small enough to copy on a scanner, and every damn one of them has missing dimensions right at the "fold".--And its amazing how many parts were drawn right in the center of the drawing where the fold is. I hate it when there is no overall general arrangement to see how the myriad of pieces all fit together. With this engine they supply a lot of very good photographs with the build notes, and I guess you have to suss out how all the parts go together by finding them on the photographs.--I'm not accustomed to working like this. George you are right---the piston crown is far too thin as drawn, as are many other parts, (in my estimation). First thing I will do today is correct the model, second thing is to return a phone call to Toronto about some "real work" I was asked about bidding on.


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## Brian Rupnow (May 12, 2014)

Gradually I am getting this sussed out. The modeling is almost completed. I haven't done anything with the timing gears yet. You see one section taken thru the engine at the center of the cylinder, one section taken thru the center of the engine at the camshaft, and one blow up of the rocker arm area. Something is very fishy with the crankshaft. The bill of material calls for 3 main bearings (in red) all with a 10mm i.d., but the center bearing is setting on a portion of crankshaft that is called up as being 12 mm diameter. The crank is a tad short on one end too. I will read thru all of the design notes tonight and see if I can pick up any clues.---The original designer MAY have meant the center bearing to be 12mm i.d which would make the crank correct in that area, but the crank would still be a bit short on the left hand end. The section thru the camshaft looks okay at a quick glance, but I may be missing a spacer on the right hand end to help position the bearing.


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## Brian Rupnow (May 12, 2014)

gus said:


> OK. Gus just got infected too. Will build a Jaguar too but will be 2015. Geared cam drive and push rods.
> 
> Brian, When can see your Canadian Nemett-Jaguar going.



Gus--It's summer time!!! I am not in a rush to machine anything yet. I will first complete all of the modeling as per the original drawings, then decide what changes I wish to make, then model all of the changes. I am not going to make any forecasts about "when" I will have a running engine.---Brian


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## Jasonb (May 13, 2014)

As I said read through the threads on ME forum, the bearing spec has been covered, you want a S61801 which is un shielded, 12mm bore,21OD, 5mm thick

Spring keeps are upside down, the spigot fits inside the spring, the e-clip in the recess


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## Brian Rupnow (May 13, 2014)

Jasonb said:


> As I said read through the threads on ME forum, the bearing spec has been covered, you want a S61801 which is un shielded, 12mm bore,21OD, 5mm thick
> 
> Spring keeps are upside down, the spigot fits inside the spring, the e-clip in the recess


Thanks Jason----Brian


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## Brian Rupnow (May 13, 2014)

Didn't get much play time today.--Worked all day on that small contract I went to Toronto to see about yesterday. I did manage to get the correct mod 0.8 gears downloaded and installed. When I get to my build, I will be using 24DP gears because that's what cutters I have.


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## gus (May 14, 2014)

Happy Gear Cutting. Take care. Half tooth not wanted.


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## Brian Rupnow (May 14, 2014)

Hi Gus---Actually, I haven't done that yet with my gear cutters. Will try hard not to do it this time.---Brian


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## Brian Rupnow (May 14, 2014)

I am finished modeling the Jaguar. It seems to be a well thought out engine, and I am confident that it will work as designed. The drawings are somewhat difficult to read, due in part to the fact that when they were photocopied there are dimensions missing right at the crease in the centerline of the drawing, and there are a few minor errors. On top of that there is the fact that without a completed general arrangement it I found it very difficult to figure out where some of the parts actually went on the engine. As I understand things, Malcolm Stride created the first draft of these drawings and then unfortunately passed away. --It's pretty hard to go back and tidy up your original drawings once that happens!!! I haven't bothered with the exhaust pipe nor with the carburetor, as I will not be using the ones in the original drawings. There are a lot of things that I like about this engine. There are one or two things that I really don't care for, but they are cosmetic. I really don't like the square box shape of the crankcase--it looks like something you would find on a Russian tank!! The nicely rounded profile of the cam chain cover doesn't go with that box shaped crankcase. However, as I said, these features are cosmetic and will not detract from the running of the engine. now I will resave all of the files as a different part name and begin to make the changes I want.----Brian


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## Brian Rupnow (May 14, 2014)

The Jaguar is morphing into something else----


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## petertha (May 14, 2014)

Brian Rupnow said:


> The Jaguar is morphing into something else----



 Nice work Brian. Look forward to the build. 

 - By 'something else' you mean you are converting from original glow to spark ignition, or...? (I don't know what the original Jaguar was designed around).

 - if I understand, you converted original timing gears from metric to Imperial because you had cutters. So did that move the stock camshaft center relative to crank? Or maybe that remained & just the idler gear moved? I guess it doesn't matter if you are producing  all new plans anyway, just wondering.


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## Brian Rupnow (May 15, 2014)

Petertha--I haven't got that far yet, but will today. In all probability, the shaft centers will remain the same and only the idler position change. I will know by the end of today. This engine, at 6:1 compression ratio will run on either conventional spark ignition or on glow plugs and methanol.----Brian


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## Brian Rupnow (May 15, 2014)

Okay--There is a lot going on here, some you can see, some you can't. The original cam bearings called for were 4mm i.d. x 12mm o.d. x 4mm thick. I had a pair of new bearings left over from my Atkinson build that were 5 i.d. x 16 o.d. x 5 thick. I bored out the outer case to accept them and monkeyed with the cam spacers at each end to have an extension that slid into the bore of the bearings to make up the difference between the 4mm shaft and the 5 mm bearing bore. The green cam shaft cap had to grow from 12mm dia. to 16nn dia., and now it sets in flush with the outer side of the main housing to prevent fouling the main bearing support (that will show up better in the next post.) The cam shaft is extended out through the gear case and that yellow thing on the right hand end of the cam is the ignition cam. I have to put a hole in that case for the shaft to pass through, and an oil seal. I wanted to make the camshaft something in imperial, but there is no close conversion to get a 4mm shaft into imperial. 1/8" is too small and 3/16" shaft  (4.762mm) would have been too large to allow a proper spacer inside my 5mm bearings, so I left the shaft at 4mm dia.


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## Brian Rupnow (May 15, 2014)

More interesting stuff happening here. The original plans had two different sizes of crankshaft bearings, a 12mm on one side and a 10mm on the other side, plus an additional bearing at the outboard end of the bolt on bearing support to help support the weight of a propeller.  I had a pair of 10mm bearings, so have eliminated the third bearing and went with a 10mm brg on each side of the crankshaft.The light blue bolt on bearing support has become much shorter and tucks in tight to the side of the main crankcase so that the new flywheel basically fits right over top of it. It had to grow in diameter to suit my 10mm bearings which have a larger outer diameter then the original bearings which were called for, so actually overlaps the cam shaft cap---That is why the cam shaft cap now sets in flush with the outside of the main crankcase. The cast iron liner has been eliminated. The cylinder is now cast iron instead of aluminum and has now been given a 7/8" bore, with an extension piece which extends below and above the original cylinder bottom and top faces to end where the cast liner originally ended. The gudgeon pin and cylinder cross bore have changed to 3/16" diameter. The piston is now 7/8" diameter and the crown area has been thickened up. The ring grooves, rings, and cylinder grooves have all changed to 1.5 mm because that is the width of parting off tool that I have. The flywheel is much larger in diameter than the original, and the support feet have been extended to give adequate backing so that the flywheel doesn't hit the table. The bolts which secure these bolt on angles to the sides of the crankcase have been moved down considerably in the crank case sides. The cylinder head, valves, and rocker arms are basically unchanged.


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## Brian Rupnow (May 15, 2014)

The timing gear cover has underwent a shape change and is squared off at the top to match the squarish profile of the main crankcase. It has also been widened in critical areas to act as a base for my standard Chrysler ignition points. I now have to change the gears from metric mod style to 24DP to match the cutters that I have and hope that I can fit them into the "existing" gear cover.


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## Brian Rupnow (May 15, 2014)

Jason--That cyan blue spacer ring I added should keep the crank positioned.


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## Brian Rupnow (May 15, 2014)

So-----Here we are, 99% finished, complete with Chuck Fellows style carburetor. Since my gear cutters are 24 dp. which cut larger gears than the .08 mod that this engine was originally designed with, the gear cover grew proportionally. I like it. It does have its own very distinct identity now, and as such, will be renamed the "Canadian Cub". I will be starting to make detail drawings sometime this week. I don't think I will post any drawings now, except for the general arrangement, because I have found that there are always changes as I go through the build, and I don't want to have to be constantly revising posted drawings. The drawings will all be done in inch decimal measurements, and the purchased components are a bit of a mish-mash,because the bearings I have used are all metric, while the sparkplug will probably have imperial threads. (Its becoming increasingly more difficult to get inch measurement bearings anyways). So----I assume that since the drawings will only be of use to model engineers in Canada and USA because of the inch measurements, who wants a copy of the finished drawing package once I have worked through the engine build and updated the drawing package to be correct? Let me know now please.


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## Brian Rupnow (May 15, 2014)




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## Brian Rupnow (May 16, 2014)

Jeez---I've been detailing my brains out. I'm up to 27 drawings now, and I have a question. I want to build the flywheel in the attached drawing, but the high price of brass is killing me. I do have enough polished 1/4" brass plate which some kind soul off the forum gave me 2 years ago, to cut 3 circles 1/4" thick. I also have enough left over 2" diameter cast iron "butts" to make the smaller diameter. I'm wondering--If I laminate all of the plates and the chunk of cast iron, using a circle of 6 hidden #8 bolts (with the bolt heads counterbored on the side which faces the engine)--would the 3 pieces of polished brass plate blend well enough when turned on the lathe together that the laminations wouldn't be obvious?


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## Swifty (May 16, 2014)

Can you sweat solder the brass plates together and then loctite the cast iron centre in, just a thought.

Paul.


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## Brian Rupnow (May 16, 2014)

Swifty, I don't really know. Its a very large area. I seem to do well soldering and silver soldering small things together, but something 3" in diameter might be a bit beyond my capabilities.


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## Swifty (May 16, 2014)

Years ago, I needed a very thick piece of copper for an EDM electrode, I had pieces that were thinner so I just heated up the pieces individually, painted with flux and let the lead solder flow on the surface of each. Picked up one piece with tongs and placed it inverted on top of the other piece, a little bit more heat, a couple of clamps and it turned out great.

I have great confidence in you ability Brian, I'm sure that you could do it.

Paul.


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## Brian Rupnow (May 16, 2014)

Swifty--I'm setting here laughing. There is definitely something a little funny about somebody on the farthest side of the planet having more confidence in my abilities than I do.--I assume you were using soft (plumbers) solder----Right?--Brian


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## Swifty (May 16, 2014)

Yes, that's right Brian, just ordinary plumbers lead solder (or whatever they make it out of these days)


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## Tin Falcon (May 17, 2014)

Jasonb said:


> Replied on the other side.
> 
> J



REALLY !!! PLEASE if you have something to say about this post say it here . 

Tin


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## Brian Rupnow (May 17, 2014)

This morning I'm up to 37 drawings, and I haven't done the general arrangement yet, but all of the part details are finished. In typical Canadian fashion, this design is 95% imperial "inch" measurements, and about 5% metric. That 5% is because the metric bearings demand metric bores and metric shafts. Some of the things that were done originally in metric just don't convert worth a damn. The nearest "reasonable" imperial dimension is so weird that you can't buy a reamer that size, so I stuck with metric in a couple of places. One of the drawings is a sub assembly of parts found on other drawings, so that means there are 36 "unique" part details. Many of these parts are "two required" so I believe there are something like a total of 99 parts, but that includes 4 bearings, a couple of nuts and bolts, and all of the carburetor parts. Definitely not an engine you would build over a weekend. If I'm not very careful, I may find myself starting to cut metal this week.--Thats okay. We are having a wet cold, totally sucky summer, following a long cold wet sucky spring, following the winter from hell.---I may never go outside again anyways!!!


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## Brian Rupnow (May 17, 2014)

Today we made a small (very small) start. The crankshaft gear and the idler gear are both going to be 15 tooth 24DP gears. They will be 0.25" wide. The steel crankshaft gear will have two set-screws in the hub to hold it in position on the crankshaft end. The idler gear will be made from cast iron---It has no hub and will spin freely on a steel shaft. I chose cast iron for its self lubricating properties--it won't require a bushing. I had a left over piece of cast iron from another job that was 1.5" dia. and 5/16" thick. The o.d. of the gears is 0.708" I used a piece of 3/4" cold rolled steel for the crankshaft gear. I turned it to the correct diameter on the end and in what will become the hub area, then put in a 3/16" reamed bore. I set the cast iron up in my 3 jaw chuck and put a 3/16" reamed bore in it. then I used a short piece of 3/16" cold rolled steel and some Loctite to put the cast iron blank and the cold rolled steel blank together. I then drilled both pieces 1/16" for a couple of pieces of 1/16" cold rolled which will act as "drive keys'. Tomorrow I will set the cold rolled up in my 3 jaw chuck and turn the cast iron down to the same 0.708" diameter as the steel x 1/4" thick. Then I will set it up in my rotary table and cut both gears at once. Then a bit of heat to separate the pieces, and open the bore in the crankshaft gear out to 9/32", which will be the finished bore. The finished bore of the cast iron idler will be 3/16" so no farther changes will be required to it. Then cut off the cold rolled to the desired hub length and drill/tap it for two set screws.


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## Brian Rupnow (May 18, 2014)

TA-DA!!!~--Now, on to the camshaft gear. I think since I have room for a big hub on it, I will make it from cast iron too.--Cast iron leftovers are free. Brass I have to pay for!!!


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## Brian Rupnow (May 18, 2014)

It is absolutely amazing what a large portion of the day gets eaten up by 3 little parts!!!--Don't get me wrong---it didn't take the whole day. Just most of it. The rest of the day was spent building a built in cabinet in my garage for my new generator (The one I bought for the spring flood that never happened)to live in.--If the teeth on that largest gear look a little blunt on the ends, its because they are. I had the gear blank Loctited onto a shaft to turn it to finished o.d., and right on the last "truing up" cut the damn Loctite broke loose. By the time I got it re-Loctited it had gone out of center enough to demand another truing up cut, so its about 0.010" undersize on the outer diameter. That won't effect the mesh, and its hidden inside a gearcase so I'm not too worried about it.


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## gus (May 18, 2014)

Brian, 
Congrats to successfully cutting the C.I. Gears w/o half tooth.  I did a tally count.th_wav.


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## gus (May 18, 2014)

Brian Rupnow said:


>




Hi Brian.

Plan to build this engine 2015. You got me hooked.

Paul. Are you on?? . My worry is the ''one piece crankshaft.


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## Brian Rupnow (May 18, 2014)

I learned long ago to never trust the centers that my computer or I calculate for meshing spur gears.--(Yes, there was life before computers---I used to do it all with trigonometry.) Now each time I make a gear train, even a simple one with only two gears, I use the measurements that will be used in machining the final part in which the gears will be fitted, to drill and ream holes in a scrap and then mount the gears and see how well they mesh. I must have lived right this week, because they mesh just fine!!! I also discovered a bonus today.(sitting at the left hand side of the picture.) While rooting around in my cast iron short ends looking for something to carve a gear from, I spied one piece that looked a bit larger than all the rest. I don't know what project it is left over from, but it is 1.6" diameter x 2" long. The cylinder for the Canadian Cub is 1.575" maximum diameter at the flange, x 1.705" long. If I can get lucky enough to have this piece clean up and leave me 1.575" at either end, I will have a free cylinder. Dang, I love it when that happens!!!


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## Brian Rupnow (May 18, 2014)

Gus---Where did I say it was going to have a "one piece crankshaft"? I haven't yet decided exactly how I will construct the crankshaft. Granted, it shows up in the model as being one piece, but when it comes to the actual fabrication, it might be one piece, but then again it might be 5 pieces. I have made one piece crankshafts, and found it rather brutal. I have soldered them together from separate pieces. I have Loctited and pinned them together from seperate pieces. I have mig welded them together from pieces. I still don't think I have found the "perfect" way to make a crankshaft. My problem with machining one piece crankshafts is that it is an awful lot of machining, and at the end of the game, if anything is "out" the entire crankshaft and all of those machining hours go into the dumpster.


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## Swifty (May 18, 2014)

gus said:


> Hi Brian.
> 
> Plan to build this engine 2015. You got me hooked.
> 
> Paul. Are you on?? . My worry is the ''one piece crankshaft.



Gus, I will think about it, although I'm keen to make a multi cylinder engine next.

Paul.


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## Brian Rupnow (May 19, 2014)

We have a cylinder!!!---Hot off the lathe, literally!!! the bore is reamed to 0.875" but not finished in any other way, yet. I still have to drill a ring of threaded holes at the cylinder head end and a ring of clearance holes at the end where it bolts to the crankcase, but the scary part is done. My parting tool is 1/16", so thats what the grooves and lands are. Gee---does it ever look small!!! I am not going to use a liner, so you can see that a bit of skirt sticks below the flange and about .040" above the top.


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## Brian Rupnow (May 19, 2014)

I decided that I would drill and tap a piece of bar and bolt it to the threaded cylinder end, to allow me something to use as a "witness surface" to ensure that the bolt pattern in the far end of the cylinder would get drilled in the correct angular orientation. Then I decided "Well darn---If I have to drill five holes in a piece of bar, why not just make the cylinder head?" I was doing fine until I drilled and counterbored the second last hole. As soon as I was finished drilling it and stepped back from the machine, I thought,---"Damn, that looks like its a long ways back from the left end of the bar----". Sure enough--instead of the .494" ordinate dimension on the drawing, I had for some reason picked up on the .748 R just to the right of it about an inch. CALMLY---I reset the dials and redone the second last hole---and by Golly, I think I may get away with it. I think that with a little creative blending in that area, when the .748" radius is cut on the cylinder head the "bad hole" is going to go away!!!  On a positive note, all of the bolt holes I had drilled in the bar using ordinate dimensions lined up perfectly with the threaded holes in the cylinder. I don't have readouts on my machines, so everything is set up using the dials for X and Y positioning. I am not a big believer in "marking through" with transfer punches. I have found I have trouble every time I do that.


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## gus (May 19, 2014)

How come,I did not think of using C.I. . Will be following your Canadian Nemett Thread.


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## Brian Rupnow (May 20, 2014)

I spent a great portion of the morning figuring out the cams for this thing. (actually, the same cams used in the original Jaguar design) I want it to turn the opposite way to the original Jaguar engine, because I use my variable speed electric drill as a starter, and when the engine must be turned counterclockwise to start, the chuck "unloosens" itself from my "starter spud". I'm not sure why I found this so difficult, but it has a lot to do with the fact that I have built so many hit and miss engines with only one cam that  two cams confused the daylights out of me. At any rate, I got it sussed out, but it was a struggle. The engine will turn clockwise when viewed from the flywheel end. Since there are 3 gears in the timing gear train, the camshaft revolves the same direction as the crankshaft. The intake valve begins to open 15 degrees before top dead center and closes 45 degrees after bottom dead center---a total of 240 degrees of "cam influence" on the tappet. The exhaust cam has the same profile as the intake, and begins to open 40 degrees before bottom dead center and closes 20 degrees after top dead center, again a total of 240 degrees of "cam influence".


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## Brian Rupnow (May 21, 2014)

My God!!! I feel like I have just excavated a hole big enough to hold a Toyota, and deep enough to come out somewhere in the Queensland!!! This is one of those times I envy you guys with the cnc equipment.--Brian


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## Brian Rupnow (May 21, 2014)

I am really surprised at how small this is turning out to be. For having such a large (7/8") bore, it is half the size of a comparable hit and miss engine.


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## Brian Rupnow (May 21, 2014)

Okay---About the crankshaft.--As you can see, its a hefty little rascal--and its only 3" long!!! I have been wanting to try some of the "stress proof" steel that seems to be so popular for making crankshafts out of. Yesterday I got a real 'buy' on a 12"  end at my metal suppliers, so I will be making a one piece crankshaft.---The first crankshaft anyways----


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## gus (May 21, 2014)

Brian Rupnow said:


> Okay---About the crankshaft.--As you can see, its a hefty little rascal--and its only 3" long!!! I have been wanting to try some of the "stress proof" steel that seems to be so popular for making crankshafts out of. Yesterday I got a real 'buy' on a 12"  end at my metal suppliers, so I will be making a one piece crankshaft.---The first crankshaft anyways----




Hi Brian,
Please post when cutting the crankshaft. Gus has yet to cut such one piece crankshaft.Will monkey see, monkey do.
 I am about to make an excavation to reach Paul in Dandenong,Victoria,Australia.


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## Swifty (May 21, 2014)

Gus, if you do the bore first in the lathe, this removes a lot of material, see my build.

By the way, if you end up in Dandenong with your excavation, you will miss me, I live in Mount Martha.

Paul.


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## Brian Rupnow (May 22, 2014)

Today I bored out the hole for the register on the bottom of the cylinder to fit into (my 1" reamer was too long--my mill didn't have enough headroom to let me use it.) and drilled and tapped the 6 holes to match the bolt pattern on the flange of the cylinder. My God----What filthy little piggies those bolts are when trying to fit them into place. I went down street and bought a set of ball end hex wrenches because it was the only way I could get at them to tighten them.
An almost direct cross reference for M3 bolts is the #5-40, which is a bastard thread size, but I use it a lot because it is the thread you can put on a 1/8" rod with no modification to the rod diameter. After bragging yesterday about how well my bolts lined up when I drilled the bolt pattern using the dials on my mill, Hubris bit me on the arse today. Five of the bolts went in just the way they were supposed to. One of the bolt holes wandered off just enough that I had that cylinder on and off 3 times, "stretching" a bolt hole. That cylinder is cast, and you can't crank down on any one bolt to draw things into place or the flange will crack. I also tapped the crankcase for the capscrews that hold the support feet on, and made up the support feet from some 1/8" thick aluminum angle.


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## Brian Rupnow (May 22, 2014)

I had to break down today and buy an "Old mans work-stool". My arthritis has been so exceptionally bad from the cold wet spring we are enduring that my legs and lower back have been killing me when standing at the mill and lathe. I'm not sure if this is going to work for me or not. It feels weird, setting down to run the lathe or mill. Oh well, I only paid $10 for it from the "buy and sell" adds in the local paper, so if I find I can't use it, I'm not out a fortune.


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## gus (May 22, 2014)

Hi Paul, Hi Brian.

I am so envious of you guys with big lathes,mills and big machineshop and could take bigger cuts.When you live in flat and the balcony is your workshop,putting in bigger machine tools is not an option.So I have to live with the mini lathe and mill and take mini bites into the bar stock to cut Nemett Engines.:rant: 
Making good progress on the crankcase. The bearing housing will snug fit in. Will bore the other end followed with the excavation to Mount Martha and Paul Swifty. Gus watching both Brian's and Paul's thread. Still very much a beginner and prone to goofs reading dimensions/details and slip on the last cuts.:hDe: My darling wife thinks I am crazy at making engines and not making $$$$.


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## Brian Rupnow (May 22, 2014)

Gus--I've heard it said that "Size isn't everything!!"---But I don't think that applies to shop machinery. As far as making goofs reading dimensions--I do it myself, even when reading my own drawings. I would hate to have had to make my living working as a machinist.---but I love doing it as a hobby. The world doesn't always have to make sense.-------Brian


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## Swifty (May 22, 2014)

Gus, you do amazing work with small machines on your balcony, having larger machines can be a problem with smaller parts sometimes.

Paul.


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## Brian Rupnow (May 23, 2014)

This is my mornings offerings to the Machine Gods.---Sure doesn't look like much!!! The big disc (big being a relative term) is the holder for one end of the crankshaft bearing, which is shown setting on top of it. I like to make the bore about .001 to .002" larger than the actual bearing outer diameter. This way, when I get everything final machined, I can put a bit of Loctite around both bearings and install a straight alignment bar just before I seal up the case and tighten all of the bolts down. If there is any minor machining misalignment the bearing can shift around a little bit until it is perfectly aligned with no bind. When left overnight, the Loctite takes on a permanent set, and there is no bind on the shaft and/or bearings. The small disc with the shallow counterbore fits into the hole in the side of the crankcase behind the small camshaft bearing  and serves to plug the hole and to give a definite end position to the camshaft. The 10mm crankshaft bearings were reclaimed from a machine of some kind?? that I dismantled, and the camshaft bearings were originally used on my first build of the Atkinson engine.


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## Swifty (May 23, 2014)

Brian, if you check out my Nemett build, you will see my solution to make getting the screws in and tightened much easier.

Paul.


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## Brian Rupnow (May 23, 2014)

Paul--I can get at my screws---just not easily. The ball end hex wrenches help a great deal. I will not have that cylinder on and off enough times to justify modifying the cylinder.----I hope---The secret is to put all the bolts in place before setting  the cylinder onto the crankcase.


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## Brian Rupnow (May 24, 2014)

I really wasn't sure how to make this part. It could have been done any number of ways, but the lathe removes material so much faster than the mill that I decided to take a lathe approach. I started with a 6" square piece of 1/2" aluminum plate, scribed a circle on it larger than the largest dimension I would need from the center to the extreme outside edge of the finished part, roughed it out on the bandsaw, then used the old sticky tape trick to true it perfectly round. I then reversed the jaws in my lathe, gripped the plate, and used my home brewed trepanning tool to chew most of the unwanted material out of the center, then used a left hand carbide in the toolholder to finish the bottom of the excavation nicely and turn the O.D. of the spigot to a nice 1.181" diameter. I then drilled out the center in progressive steps up to 31/32" and finished up with a boring tool to get the exact bearing diameter. Tomorrow I will remove the outer rim with my bandsaw and finish the profile of the plate.


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## gus (May 25, 2014)

Swifty said:


> Gus, if you do the bore first in the lathe, this removes a lot of material, see my build.
> 
> By the way, if you end up in Dandenong with your excavation, you will miss me, I live in Mount Martha.
> 
> Paul.



Tunnel done and access shaft to ground level done too but now lost at Dandenong. Never thought I would see day light. Been nailing biting,milling
crankcase on a mini mill. Quite happy with the accomplished task.


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## Brian Rupnow (May 25, 2014)

Sometimes when I have an odd shaped part, with many holes to be drilled and no good "witness" edges to do my layout from, I print out the part at 1:1 scale, and find a starting point (in this case the bearing hole). I drilled a couple of the #4-40 threaded holes as far as I could get from the center hole, then located the paper layout (glued to a cardboard backing) using one cap screw and one drill of the correct size. I still used ordinate dimensions and the dials on my mill to locate all the holes yet to be drilled, but I had a good visual reference to confirm that yes, I had counted the correct number of dial revolutions and the holes were going to be where I intended them to be. You will see one area close to the large hole where there are two holes drilled that weren't marked on the drawing, and one hole marked on the drawing that isn't drilled. That is not a mistake. It is the result of a small design change after I had cut out and glued the drawing to the cardboard.


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## Brian Rupnow (May 25, 2014)

The other really great thing about an accurate 1:1 printout glued to cardboard, is that after all of the drilling is finished, you can remove the print, color the metal with layout dye, wait 5 minutes and then put the cardboard back in place and scribe around it.--Then, presto---You have al the outer profile to cut to. since it is only a profile and not critical really, saw close to the scribed line on the bandsaw and then file to finished size.


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## Brian Rupnow (May 25, 2014)

And we end up with a quite nicely executed timing baseplate!! I will now use the outer profile of this part to scribe an outline on a rather nice piece of bronze plate, which will become the actual gear cover.


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## Swifty (May 25, 2014)

Nice going Brian, sticking the printout on was a good idea to enable you to check hole positioning.

Paul.


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## gus (May 25, 2014)

Brian Rupnow said:


> And we end up with a quite nicely executed timing baseplate!! I will now use the outer profile of this part to scribe an outline on a rather nice piece of bronze plate, which will become the actual gear cover.



Cheers to WW-1 and 2014 technology. Planning to build the single cylinder engine in 2015. This is great idea. th_wav


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## Brian Rupnow (May 25, 2014)

Today was a gorgeous day.--It felt like summer for the first time this year.--No clouds, high of 28C  (about 86F) ---God, I loved it. Took good wife for a drive in the country and out to Creemore for lunch. (Creemore has a micro-brewery that makes amazing beer.) The rest of the day I whittled away at the crankcase, boring holes for camshaft bearings and timing gear baseplate. All the holes lined up, which is always a GOOD thing. Here is a picture of the timing baseplate bolted to the crankcase with all of the gears dummied into position.


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## gus (May 26, 2014)

Looking good. I can almost hear this engine running.

 2015 will build this engine. The Lynx Engine will take some time------at least two months. Learned no to rush. Do it right the first time.

On my part,I am working on the un-ending small details.


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## cfellows (May 26, 2014)

Nice work on that baseplate, Brian.  

 Chuck


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## Brian Rupnow (May 26, 2014)

Many good things happened today!! The other side of the crankcase got bored and the bearing holder inserted. The machined bearing cap which covers the camshaft bearing  on the non gearcase side was installed--not Loctited yet, but it fits in very nicely. I didn't have any 4 MM shaft to make the camshaft from, but I turned a piece of 3/16" rod to 0.157" which is 4 mm and made the camshaft and installed it along with its bearings into the crankcase. (The cams get made as separate pieces and attached to the camshaft at a later date). The camshaft  bearings which I reclaimed from my first build of the Atkinson were 5 mm so I made up combination cam spacers/ bushings to match the 4 mm camshaft to the 5mm bearings. I made up the pedestal support for the idler gear and installed it, and after assembling all of the gears, Hallelujah--they mesh just fine. As you can see by the pictures, I have to shorten up my bolts and trim some off of the inside edge of the main bearing housings--(they should end flush with the inside of the crankcase.  All in all, a very satisfying day!!


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## Jasonb (May 27, 2014)

Brian, won't you also need to bore the bearing hole deeper so the bearing also sits flush with the case insides or did the sides come out a bit thinner?


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## Brian Rupnow (May 27, 2014)

Jason--You are absolutely correct. The bearing holding plates on both sides of the crankcase were both machined from 1/2" plate, and not trimmed to length when the pictures were taken. I measured out how far they extended in past the inner walls of the crank-case this morning and shortened them both up by the amount required to bring them flush on the inside. I did have to deepen the counterbored bearing pocket in the non-timing gear side to bring the bearing into its proper position as well.


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## Brian Rupnow (May 27, 2014)

There was a whole lot of breath holding and finger crossing going on at my house this morning. I put all of the cosmetic chamfers and indentations in the crankcase. These are a feature which add absolutely no value to the way the engine will perform, but are for "pretty". This is usually the point at which something jams, lets go, or plain screws up on a part that has a ton of work already done correctly on it, and destroys the part. However, I seem to have escaped unscathed, and the only real machining left on this part is the hole pattern in the bottom that the oil sump attaches to and an oil filler hole.


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## Brian Rupnow (May 27, 2014)

I still have to do a bit of creative carving, deepening counterbores, etcetera, but by and large the overall "body" of this engine is complete except for the gear cover. For one horrible moment I thought I had reversed a bolt pattern in the top of the cylinder, but then realized that the bolt pattern at the bottom of the cylinder lets me rotate the entire cylinder 180 degrees, and thats what I had done. A quick disassembly and reassembly of the cylinder and crankcase got my heart slowed down again.


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## Swifty (May 27, 2014)

Looking very nice Brian, you are certainly correct about having to be careful when you have put a large amount of work into an item. It would be a shame to make a mistake on a part that you have sweated over for days.

Paul.


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## Brian Rupnow (May 27, 2014)

I think that is a syndrome known as "Model machinists angst."---The more work you put into a part, the more you are concerned about screwing it up. --Brian


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## Brian Rupnow (May 27, 2014)

Today I bit the bullet and ordered a 36" x 60" ergonomic rubber mat to stand on. The stool just doesn't cut it. I'm in and out between my little machine shop and my computer about 50 times a day, and every damn time I turn around the stool was in my way. I could actually work while seated on it, but I have come to realize that hardly any of the machining I do is constant machining. I'm up and down, in and out more times than I ever realized.


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## gus (May 27, 2014)

Brian Rupnow said:


> I think that is a syndrome known as "Model machinists angst."---The more work you put into a part, the more you are concerned about screwing it up. --Brian



Hi Brian,
I share this ingrained fear with you. The Nemett-Lynx crankcase has 8 more M3
thread holes to do. The Bearing housing have one bearing to fit in.
To counter the ''Jinx'', I take many tea/pee breaks.

Good Luck.
Take care.


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## Brian Rupnow (May 28, 2014)

Today I think I will do one of the easiest, but most vital parts of an engine---the piston. I have been really "pouring it on" in my little shop, but today I want something quick and easy to machine. I have always subscribed to the "cast iron piston in a cast iron liner" theory. but Malcolm Stride uses an aluminum piston in a cast iron liner and seemingly gets away with it. He does say to leave the piston diameter about .002" smaller than the i.d. of the cylinder to keep from having problems with piston expanding and seizing in the bore.-I have been taught to never use this combination, but this time I will try it and see what happens.


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## Brian Rupnow (May 28, 2014)

I think I am going to try making my own cast iron piston rings. I have not tried making them before. I did order a set of pre machined cast iron rings for one engine but I could not get them to seal. I have been using Viton o-rings with great success, but as I develop more and better machining skills I would like to move into the world of cast iron rings.---Brian


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## Brian Rupnow (May 28, 2014)

This is as far as I can go with the first stage of machining. A piece of 1" diameter aluminum is turned to 0.874" for sufficient length to get the piston length and about 1/4" more for cut-off tool allowance. The end is opened out to 0.787" diameter x .174" deep using a succession of drills, end mills, and finally a boring tool. The ring grooves are put in at this time also. In theory, a piston ring thickness is supposed to be 25 to 30 times less than the piston diameter. In reality, my thinnest parting off tool is .062", and that is about as fine as I am comfortable with when I have to part off the rings from a piece of cast iron. So---the rings will be just a couple of thou. less than .062" thick, and I am going to shoot for 1/16" square cross section on the rings themselves. you will see 3 grooves on the piston. The two nearest the end with the counterbore are ring grooves. The one farthest away from the counterbored end delineates where the length of the piston will be. In spite of all the good advice i have been given about parting off, my heart quails at the thought of trying to completely part the piston off from the main stock. I will now take it over to the saw, cut it off, then put the turned end into the lathe and face off the sawcut portion to line up with the groove already turned.


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## Brian Rupnow (May 28, 2014)

From the lathe we move over to the rotary table. The piston still hasn't been cut to length. It is about 2" longer than what the finished size will be. Set upright in the rotary table, and centered under the quill, the slot for the con rod is milled to depth. By milling the slot in the Y axis  (away from you and towards you), this makes it very easy when I go to drill the gudgeon hole. My rotary table is locked so it can not rotate during these operations. By undoing the bolts which hold the rotary table to the milling table, I can flip the entire rotary table onto its other flat side, square it up to the mill table again, and then I am assured that when I drill/ream the gudgeon pin hole it will be at exactly 90 degrees to the long axis of the slot. I still have to drill and tap the set screw holes which hold the gudgeon pin in place before I tear down this current set-up to flip the rotary table 90 degrees.


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## Brian Rupnow (May 28, 2014)

I didn't take any picture of the gudgeon pin hole being drilled. I do however have a finished piston. There is a little trick lurking in the bottom of that slot.--The slot is deeper in the center than it is at the outside edges, to keep the ends of the slot from breaking out into a ring groove.


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## Brian Rupnow (May 28, 2014)

I have just undertook a bit of research on making rings, and it seems I may have messed up when I made the piston. My grooves ended up being about 0.50" wide x .057" deep. There doesn't appear to be any issue with the width--The ring will be parted off at about .047 to .049" thick. Where the problem lies is with the depth of the grooves I made. The information I have says to make the blank from which the rings are cut about .003" to .004" larger in diameter than the bore of the cylinder (0.875"). The inner diameter of the blank should be a match for the inner diameter of the groove cut into the piston which would be .875"-(.057 + .057")=0.761". This means that the o.d. of the ring blank will be 0.878" and the i.d. will be 0.761", leaving a net thickness of .878-.761 divided by 2=.058" ring thickness  from inner diameter to outer diameter.  It seems (and I do mean seems) that instead of a thickness of .058, I should have aimed for about .040" (close to 1 millimeter). I have gone too far to turn back now, having just spent a goodly portion of the day making this piston. I am going to make up about 10 rings using the formula I have, and heat treat them using the method described by Malcolm Stride, who originally designed the Nemett Jaguar which i used as the basis for this engine design. If it works then all is good. If it doesn't work (the danger being that rings of this thickness are very prone to breaking when spreading them over the piston to install them in the grooves of the piston.) I will only be out some time. Neither the aluminum nor the cast iron left overs have cost me anything, and I am learning something new here. I will keep you all posted as this develops.---Brian


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## Brian Rupnow (May 29, 2014)

Okay--Today I have a tiny bit more insight, courtesy of Geo Britnell. He advocates turning the o.d. of the ring blank to .0005 more than the cylinder bore diameter. Even though my piston groove is 0.57" deep. George says to make the i.d of the ring blank .080" less than the blank o.d. This will give a ring approximately 0.040" or 1 mm thick. He said that having the piston groove deeper won't hurt anything, the rings will just "float" a bit more concentrically. Keep in mind that the rings get split, then wedged farther open at the split, then heat treated to take a "set" and then they have to be compressed to get them into the cylinder. Then the end gap of the ring is adjusted to about 0..002" to .003" with a diamond file. The fact that the ring is now only 1 mm thick lets it have enough springiness to install it over the piston and into the grooves without breaking the ring. John---As far as compression gasses getting in behind the ring and forcing it out against the cylinder wall goes, I am somewhat skeptical of this actually happening.


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## Brian Rupnow (May 29, 2014)

Today I will build the con rod and cap, if I can find enough material in my shorts rack. I may even get around to the piston rings.


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## Brian Rupnow (May 29, 2014)

I hunted around in my "shorts" bin until I found a piece of 3/8" aluminum bar with a minimum number of shallow war wounds on it. I laid out the con rod and drilled the four diameter 0.158" holes to form the radii in the corners. I also drilled and reamed the 3/16" hole thru the small end of the con rod. I drilled and tapped the other end of the rod to receive the rod cap. I made up the rod cap as a separate part and drilled clearance holes, then bolted it to the big end of the rod. The next step from here is to drill and ream the big end hole, which will be half in the rod and half in the rod cap. Then I will fully cut out the outside profile of the rod and move to the next stage where I mill away 1/16" of material on each side of the rod, leaving only the bosses at both ends a full 3/8" wide.


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## Jasonb (May 29, 2014)

Brian, I know it does not give materials on the drawing but that really wants to be HE15 or 2014 to you not whatever is in the scrap pile. That grade is the High tensile one that it says to use in the article

J


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## Brian Rupnow (May 29, 2014)

Jason--all of the aluminum I have is 6061 T6. Thats what I use for all my con rods, and other engine parts.


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## Brian Rupnow (May 29, 2014)

So--There we have it. A con rod and con rod cap finished. I must confess not to using the rotary table. It takes too long to get everything set up. I mill the flat on both sides of the rod in the milling vice, staying about 1/16" away from where the radiused ends are. Then I turn a spigot of material .001" larger than the big end bore and clamp the rod to it. The lathe makes short work of putting a radius on the big end. Do one side, then flip it around and do the other side. For the small end I do the outside of the radius on my belt sander, except where the body of the rod is in the way. Loctite a piece of 3/16" crs into the bore, letting it stick out about 1" each side. Then I drill the oil hole in the small end and drill right on into the 3/16 cold rolled. Then Loctite a short piece of 1/16 crs into that hole so it locks the 3/16" into place. Then I turn the small end in the lathe the same way. After 5 minutes with a small file and some fine sandpaper, I'm finished. It might not be jewelry quality, but it is dimensionally correct and will be hidden inside a crankcase.


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## Brian Rupnow (May 30, 2014)

Good morning, Guys and Gals.--I woke up feeling rather cranky this morning, so decided it would only be appropriate to make a start on the crankshaft!!! I am going to turn the crankshaft from solid, using a new method that I first seen used by Gail in New Mexico on his original opposed piston engine. I will also be trying out 1144 stress proof steel for the first time. Stay tuned. You may learn something new, or, at the very least have a chance to laugh and call me the Canadian Pretzel maker.----Brian


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## Brian Rupnow (May 30, 2014)

First step was to cut off a length of 1 3/8" diameter stock about 1/8" longer than the overall crankshaft length, face both ends, and turn the outer diameter to an exact 1.300" diameter. Next step is to completely finish turning one end (in this case the end without the reduced diameter for the timing gear) and to make sure I had the .039" x .472 diameter boss turned as well. There is really too much material sticking out past the chuck jaws, which makes things want to chatter. I was using a carbide at 920 rpm, taking .005 deep radial cuts. When I got close to finished diameter I backed off the depth of cut to .002 radial, which got rid of the chatter, turned the part until it was .002" oversize, then finished to size with #180 and #220 grit emery cloth.  That is a lot of material to leave on, which means shutting off the lathe every 20 passes with the paper and trying the bearing to see if it fits yet. I don't trust myself nor my machine to turn the diameter to finished size. Bitter experience has taught me to leave some material on and remove it with emery cloth. Its a time consuming pain in the keester, but I don't ruin parts by turning them undersize.


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## Brian Rupnow (May 30, 2014)

The crankshaft is now completely turned at both ends. People were right---the 1144 stress-proof steel is nice to work with. I haven't done anything yet to actually make the crankshaft bend out of "true", but that step will be next. The extra bit of shaft which sticks out past the gear will get trimmed off flush with the face of the gear.


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## Brian Rupnow (May 30, 2014)

Now this is where it begins to get ahh--Exciting!!! The crankshaft is set up on parallels in the milling vice and one side is milled away, right down to the .472" diameter boss. Then it is flipped over, again rested on parallels and machined down to the .472" diameter boss again. --I did cut away most of the metal to be removed on the bandsaw before setting up in the mill. Now---How much did the crankshaft twist out of true when I took this big slab of each side?----good Question. My 3 jaw chuck is about .003" total indicated runout out of center. (That is true out of center by .0015)  I held one end of the crank in the 3 jaw chuck and indicated the opposite end while rotating the chuck thru 360 degrees, and got a reading of .010" TIR  which is about .005" out of true center. This doesn't concern me much. I have learned that these damn small crankshafts are like a piece of spaghetti. Once all the cutting is done, I will hold one end in the chuck and tap the other end around with my dead blow hammer (little taps) until it moves into a "zero" run out position.


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## Brian Rupnow (May 30, 2014)

The crankshaft is now machined as much as it can be, until I build the crankshaft turning fixture. The total indicated runout is now up to .013 TIR.as measured in the picture. After I make the turning fixture, and do the final cut on the rod journal portion of the crankshaft and tap two holes for the counterweights, then I will get out my trusty deadblow hammer and "straighten" the crank.


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## Brian Rupnow (May 30, 2014)

For those who are interested, this is what the crankshaft turning fixture looks like. It will have to be drilled and reamed in the 4 jaw chuck in my lathe. It could also be done on the mill, but I wouldn't be able to really guarantee that the center of the drilled and reamed hole would be parallel to the central axis of the main outer diameter, and that is quite critical.


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## Brian Rupnow (May 30, 2014)

So--I am about to ride off--to the couch and a drink of wine!! As far as I know everything I have done today has went extremely well. Of course the fat lady won't sing until tomorrow when I get the crankshaft and jig set up in the lathe and turn the rod journal. I will leave you now with this loverly picture of my jig in the 4 jaw chuck. I hate setting up that 4 jaw worse than snakes, but it certainly does the job well. I have since finished the jig all except for the sawcut, which will happen tomorrow. Thanks for looking.---Brian


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## Brian Rupnow (May 30, 2014)

I have rethought this crankshaft turning fixture a little bit. I have a lot of work into it, and there is only a very thin web of material left holding the two sides together after the sawcut is put in. As a safety measure, and to aid in clamping the crankshaft, I have added provision for two 1/4" socket head capscrews. If you make one, just make sure the counterbores are deep enough to totally bury the head of the capscrew, because this thing has to go back into my 3 jaw chuck to turn the con rod journal on the crankshaft.


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## gus (May 31, 2014)

Brian Rupnow said:


> I have rethought this crankshaft turning fixture a little bit. I have a lot of work into it, and there is only a very thin web of material left holding the two sides together after the sawcut is put in. As a safety measure, and to aid in clamping the crankshaft, I have added provision for two 1/4" socket head capscrews. If you make one, just make sure the counterbores are deep enough to totally bury the head of the capscrew, because this thing has to go back into my 3 jaw chuck to turn the con rod journal on the crankshaft.



Hi Brian,

Will use this jig to machine crankshaft for Jaguar in 2015. The Lynx and other mini projects will keep me busy for the rest of 2014. Thanks for drawing.


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## ShopShoe (May 31, 2014)

Brian,

Thank you for your detailed description of your crankshaft-building process and for the drawings of the fixture. I was interested to see numbers for the runout and your home-shop method of dealing with it. I have become overly paranoid, I think, about getting perfect results when so many have talked about half-a-thous so much and implying that perfect (read expensive) equipment is required to do such work. I have attempted several things in the last year that I set aside as too rough and never posted.

Thanks again, your projects help keep me interested in this hobby.

--ShopShoe


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## Brian Rupnow (May 31, 2014)

The first picture shows the crankshaft setting in the fixture before I put it in the lathe. The second shows it in the lathe. The cut-off tool in the picture was used for all of the machining of the rod journal. I ran the lathe on its lowest speed which is 115 RPM and used a set of home made carriage stops that I set up prior to starting the lathe to ensure that I wouldn't feed the tool too far to either side and machine away material on either side of the journal. (This would have been immediate disaster and a ruined crankshaft.) i used the carriage lock-down bolt to lock the carriage in position while cutting. I very slowly plunge cut with the tool tight against one side side (tool is .093" wide), until I was no longer taking an interrupted cut. Then backed out the tool, unlocked the carriage and moved over .080" and cut to the same depth as previously cut. I kept doing this until I was tight against the other carriage stop. Measuring the resulting diameter showed me that I still had about .040" of material to remove, so I speeded the lathe up to 210 RPM and taking .002" depth of cut I traversed the carriage back and forth manually from carriage stop to carriage stop, cranking it in .002" for each pass. I stopped when the diameter reached 0.396" and then backed the tool completely out of the way and set the lathe speed at 550 RPM and used a 3/8" wide strip of #220 grit emery cloth to work the journal down to 0.394" (10mm).


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## Brian Rupnow (May 31, 2014)

Here is a little video of the crank in its final resting place.


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## Brian Rupnow (May 31, 2014)

One last crankshaft related topic, and then I promise to shut up about it. Everybody has questions about and issues with the run-out of crankshafts machined from solid. Firstly, I will say that the stress proof 1144 steel is a very nice steel to machine. Next, about the runout--I knew there would be some run-out. I don't use collets, and my 3 jaw chuck has about .003 total indicated runout.  (That means it is .0015 out of "true center").  Before I did the final machining of the rod journal, the runout had grown to about .013 TIR as measured by holding one end of the crankshaft in my 3 jaw chuck and indicating the far end of the crankshaft. After machining the rod journal, the reading had dropped back to about .006" TIR. (I won't explain the "why" of this---I'm just reporting the figures I seen.) A couple of light taps on the end of the crankshaft farthest from the chuck with my dead blow hammer, and the reading dropped back to .002 TIR which I considered was as good as I was likely to get.


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## Brian Rupnow (Jun 1, 2014)

A week ago when I was at my metal suppliers, I picked a couple of pieces of 3" diameter bronze out of the scrap bin and paid something like $20 for them. Today I decided to build a two piece flywheel with a steel center, and I used the piece of bronze with the smallest hole in the center. There is absolutely nothing I can post about flywheels that hasn't been posted about a hundred times before. I have included a picture of the "back" side of the flywheel, showing how the bronze outer ring is centered and attached to the steel center part, and a picture of the flywheel on the engine. You can also see in the shot of the flywheel on the engine how I have incorporated a pulley and my "starter dogs" into the flywheel.


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## Brian Rupnow (Jun 1, 2014)

I had purchased a piece of 3/4" thick bronze to make the gear cover out of, but I hate machining bronze. It's kind of like "Death by hot powder bombardment!!!" I have an old full face welders helmet that I took the colored lens out of and only have the clear lens in, and I use it for machining bronze. I can see where this is going to be a beast of a thing to machine manually, so as of now my plan is to make it from a piece of brass reclaimed from that 50 pound brass weight that found its way to my place.


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## gus (Jun 2, 2014)

Brian Rupnow said:


> I had purchased a piece of 3/4" thick bronze to make the gear cover out of, but I hate machining bronze. It's kind of like "Death by hot powder bombardment!!!" I have an old full face welders helmet that I took the colored lens out of and only have the clear lens in, and I use it for machining bronze. I can see where this is going to be a beast of a thing to machine manually, so as of now my plan is to make it from a piece of brass reclaimed from that 50 pound brass weight that found its way to my place.




Hi Brian,

You are not alone. I dread turn/milling brass and bronze. It gets all over me.
Watch the tinny bitty needle-like swarfs. Cast Iron gets all black and rusty.
The bathroom tiles too. Had flush and scrub after every shower. My darling boss gets mad at me for messing up her immaculate bathroom.


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## nowramfg (Jun 2, 2014)

Your descriptive texts are inspiring Brian. Any article by you or George B. gets my immediate attention.


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## Brian Rupnow (Jun 2, 2014)

I spent the lions share of today making the smallest parts on the engine. I'm still not finished---For some reason none of my grooving tools want to cut today, so the 1/8" shafts holding the rocker arms and their bearings in place are just "dummied up" for the picture. I tried 3 different times to capture a good picture of what I had done, but this is as good as I was able to get.


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## gus (Jun 3, 2014)

Hi Brian,

With every engine building and the major parts done and there seems to be no end to big pile of small parts. I have given up counting.The simple looking overhead cam box took six hours to do.:rant:


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## Brian Rupnow (Jun 3, 2014)

Six more itsy bitsy pieces this morning, Valve lifter guides, valve lifters, and spring keepers for valves. Why does the one lifter have annular marks on it?--why for oil retention, of course!!! Why doesn't the other lifter have annular marks on it?---Err---Ummm----Damn, I was hoping nobody would ask me about that---


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## Brian Rupnow (Jun 3, 2014)

I just picked up my mail today, and Roy Sholl of S&S Engineering has sent me the smallest spark plug I have ever seen in my life. It is a Rimfire VR2 with 1/4"-32 thread. I had already purchased the tap, but didn't want to use it until I had the plug "in hand". All appears to have went well. The plug comes thru into the combustion chamber at an angle of 28 degrees, and the threaded portion at the end of the plug just comes flush with the interior face of the head. This leaves the electrode a very tiny bit "recessed" but I don't think it will hurt the performance.


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## Brian Rupnow (Jun 3, 2014)

This afternoon I machined the valve cages,pressed and Loctited them into place, and using my special George Britnell tool I put a .010 to .015" x 45 degree chamfer on the area where the valve will seat. I wasn't going to post this shot, because I know the camera will pick up every bit of nastiness that is there and make it look worse than it actually is. Then I decided "Hey--This is reality!!!" The inside of that cylinder head will never be seen again once the engine is assembled, and it doesn't have to look perfect, as long as it functions perfectly and the valves seal all right. So---Here it is, warts and all!!---Brian


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## cfellows (Jun 3, 2014)

Yup, We're both working on the same end of the engine.  I got valve assembly pretty well wrapped up today.  Just need to tidy it up some.

 Chuck


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## Brian Rupnow (Jun 4, 2014)

Nothing accomplished today!! Got a call last night from a customer who has a few days engineering work so I'm busy at that for a couple of days. I needed a break from the engine anyways.---Brian


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## Brian Rupnow (Jun 5, 2014)

This morning, while waiting for a customer call back, I went ahead and made my valves from cold rolled steel. Although the valves themselves are essentially finished except for a cross hole at the end of the stem for the spring retainer, I have left the parent stock from which they were turned attached. This gives me a very convenient "handle" for rotating the valves back and forth with my fingers as I lap them into the seats. I will use a succession of 350, then 400, then 600 grit to do this. I will then drill the cross holes and cut the valves away from the parent stock. At this point I like to match mark the valves to the guides they were lapped into so I don't mix them up. ----I'm not sure that's a big deal, but ANYTHING involving valves is a big deal. I would rather spend the extra time and caution at this stage than after the engine is finished and won't run because of leaky valves.


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## gus (Jun 5, 2014)

Hi Brian,

I like your method of holding the valves for lapping. Are you using SuperGlue or Loctite. Will be turning/lapping the tappet valves next week.


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## Brian Rupnow (Jun 5, 2014)

Gus--You are looking at the parent stock that the valves are made from. I haven't parted them off yet. Read what it says in the text with the pictures.---Brian


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## gus (Jun 6, 2014)

Brian Rupnow said:


> Gus--You are looking at the parent stock that the valves are made from. I haven't parted them off yet. Read what it says in the text with the pictures.---Brian



Hi Brian,

That was a very smart move. So many ways to skin a cat.th_wav

Learned something new today. Home Gus did not think of using this method to lap valves for Webbie and your Rupnow Engine.


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## Brian Rupnow (Jun 6, 2014)

My mother used to say that small, picky, tedious jobs were like "picking fly$hit out of pepper."  This job I have just finished is about as close to that description as I ever hope to get. The valves are finished, trimmed to length, lapped into the seats, and have the springs and keepers installed. The rocker arms are set up with their own shafts, (Let me tell you some time how much I hate e-clips!!!)  I think the next move I make will be to machine the cams. Malcolm Stride gives a method where by using a rotary table in conjunction with a vernier downfeed in a milling machine, cam profiles can be generated. The rotary table turns the cam in one degree increments and the milling cutter is lowered a specified amount each time based on information given in a chart until a cam profile is generated. I have never done this before, but it sounds logical, so i will give it a whirl.


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## gus (Jun 6, 2014)

While Paul and Gus and Jim are still slogging at the Nemett-Lynx Engine,Brian is about done with Jaguar.th_wav


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## Brian Rupnow (Jun 6, 2014)

No Gus, far from it. I have to make the cams, the sump, the gear cover, the pushrods, and the ignition cam yet.


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## Brian Rupnow (Jun 6, 2014)

This is step #1 in my cam making operation. I am going to cut both cams at the same time, then separate them afterwards. The material I am using is an oil hardening tool steel, 1/2" diameter. It was left full size in the area where the two cams will be and reduced to 0.236" diameter in the area which will be adjacent to each side of the cam lobes. All turning was done at 550 RPM with the .093" cut -off tool you see in the picture. The parts were drilled and reamed to 4 mm diameter to a depth sufficient to pass through both cams and the lands on each side of them. I will now shorten the material to approx 3" long and mount it in the 3 jaw chuck mounted to my rotary table.


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## Brian Rupnow (Jun 6, 2014)

Okay--Part is in 3 jaw mounted on rotary table. Long "X" axis of part is centered under the quill. Rotary table is set on 300. Digital vernier has been zeroed on the top surface of the 1/2" round rod which will become the cam. Table stops are set so that I can only move the rotary table within a predetermined distance, which means I don't have to constantly watch my travel in X axis. 3/8" 4 flute end mill being used to make the cuts. Wish me luck!!!


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## Brian Rupnow (Jun 6, 2014)

It appears that the cam program works okay. What it wasn't clear about is the fact that when you are finished all the milling, it looks like this. The lobe portion of the cam appears to be fine. However the base circle of the cam is still based on the 1/2" diameter rod that I started with. This base circle has to be brought down to 8mm or .314". I can't do it in the lathe without cutting away the lobe of the cam. I guess my next step is over to the rotary table to finish cutting away the base circle.---More to follow.


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## nowramfg (Jun 6, 2014)

Brian, why did you set the rotary table to 300? I am needing to make some new cams also for the Lister and its sister. Also what increments ,in degrees, did you use?


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## Jasonb (Jun 6, 2014)

Brian, top of page 653 says once the offsets have been cut to do the rest of the increments at the zero lift setting which gives the base circle.

Cam has 120deg of duration with the highpoint at zero degrees you start to form the lobe 60deg before that so 360-60 = 300 and the cam is rotated through 120deg ending at 60deg with no lift. 60-299 are cut at zero.


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## Brian Rupnow (Jun 6, 2014)

Jason--Having not cut a cam this way before, I didn't understand that I was to leave the blank in the rotary table and continue cutting at zero change in the depth of cut until I had went completely around the rest of the cam. However, the blank is out of the rotary table now, and setting on the end of my desk. Odds are very slim of putting the part back into the rotary table chuck at this time and carrying on. I would never get it back in exactly the right position in a thousand years.--But wait---The tricky part of the cams is cut, and all is well. If I flip the rotary table 90 degrees and put the part back into the chuck so it is setting vertically, then use the side of an end mill to finish cutting the unmachined portion of the cam to the correct .157" (4mm) radius, would that not achieve exactly the same end result?


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## Brian Rupnow (Jun 6, 2014)

Against all odds, I was able to return the unfinished cam to my rotary table set-up (which I thankfully hadn't torn down) and as far as I can see, hit it "spot on"!!! I was able to finish milling the profile in the original manner it was intended to be finished in. The cams turned out perfect, as near as I can tell.--That was more good luck than good management, believe me!!! Now I have to separate the cams from the parent stock and from each other, and heat treat them with my oxy acetylene torch and an oil quench. ---And I REALLY REALLY hope that they don't change shape or tighten up in the bore, or anything weird!!!


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## Brian Rupnow (Jun 6, 2014)

So, there we have it---two cams, finish machined and heat treated. That shaft they are setting on is the cam shaft, but their final resting place will be inside the crankcase. I just tried them on that shaft to make sure the bores hadn't shrunk when they were heat treated.


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## ShopShoe (Jun 7, 2014)

Brian,

Thanks for showing the trials and tribulations of your cam-milling attempt. You inspire confidence for future learning of new skills. In some ways cams look more scary than gears when one hasn't done it yet.

Regards,

--ShopShoe


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## doubletop (Jun 7, 2014)

Brian  I've been a bit slow in finding this thread. As I saw somebody pointed it looks like Jaguar, Bobcat and Lynx are the engines of the moment. I now need to go and find Chucks thread.  Then I can sit back and watch the fun having already done the Bobcat and Lynx.  Pete


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## Brian Rupnow (Jun 7, 2014)

Today was just too beautiful outside to spend the whole day in my shop. It was 86 degrees F and all sunshine today. I did however sneak in for a couple of hours this afternoon and Loctited the first cam to the camshaft---a messy, nasty business, and Damn, I hope I got it in the right place. There isn't much room to work inside that crankcase, even with the crankshaft removed. I also managed to finish the intake manifold, bolt it in place, and install a Chuck Fellows carburetor on it. I'm not sure of the proportions---It looked okay on the solid model, but it kind of looks like a long necked goose in person. Perhaps when I get the rest of the engine back together things will look better proportion wise. I may have to put a spacer under my rocker arm support--the rocker arms are running uphill on quite a pronounced angle. I am going to be very tight for room between the intake pushrod and the head of the capscrew holding the intake manifold on. I may have to do a little creative counterboring there, although I'm not sure yet. Tomorrow, after the Loctite is thoroughly set up on the first cam, I have to position the second cam rotationally and Loctite it to the shaft.


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## Jasonb (Jun 8, 2014)

Brian, it looks like you have the hole for the rocker pivot and that for 3mm bearing on the same centreline rather than the bearing being offset upwards, this would account for your sloping rockers.


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## gus (Jun 8, 2014)

Brian Rupnow said:


> Today was just too beautiful outside to spend the whole day in my shop. It was 86 degrees F and all sunshine today. I did however sneak in for a couple of hours this afternoon and Loctited the first cam to the camshaft---a messy, nasty business, and Damn, I hope I got it in the right place. There isn't much room to work inside that crankcase, even with the crankshaft removed. I also managed to finish the intake manifold, bolt it in place, and install a Chuck Fellows carburetor on it. I'm not sure of the proportions---It looked okay on the solid model, but it kind of looks like a long necked goose in person. Perhaps when I get the rest of the engine back together things will look better proportion wise. I may have to put a spacer under my rocker arm support--the rocker arms are running uphill on quite a pronounced angle. I am going to be very tight for room between the intake pushrod and the head of the capscrew holding the intake manifold on. I may have to do a little creative counterboring there, although I'm not sure yet. Tomorrow, after the Loctite is thoroughly set up on the first cam, I have to position the second cam rotationally and Loctite it to the shaft.




This one engine I must build. I am crazy about push rods and rocker arms.
Seen my dad adjusting the tappet clearance as a young lad of 12. Dad had no time to explain why the clearance is so important.


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## Brian Rupnow (Jun 8, 2014)

Jason--nothing the matter with the part.--However (embarrassment)---I had them mounted upside down!!!---Brian


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## Brian Rupnow (Jun 8, 2014)

Well, for better or worse---The cams are both attached to the camshaft. I agonized all morning about just how they went on there.--The angles just weren't working out. After just about pulling my remaining hair out, I found that the value I had entered for the ratio between the gears was entered incorrectly, giving me a ratio of 1.91:1 instead of 2:1 for the ratio. Once I got that dragon slayed, things made a great deal more sense. Part of my problem also, is the fact that I want this engine to run in the opposite rotation to what old Malcolm had intended. I also whittled out a pair of counterweights for the crankshaft while I was waiting for the camshaft Loctite to set up firmly. I am actually down to only 4 or 5 parts remaining to be made. Of course, one of them parts is the gear cover, which isn't exactly simple.


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## Swifty (Jun 8, 2014)

Hi Brian, are you confident that the loctite will be enough to hold the cams in operation. I know that Malcolm used loctite, it's just that I'm a bit cautious about using it on rotating parts.

Paul.


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## gus (Jun 8, 2014)

Swifty said:


> Hi Brian, are you confident that the loctite will be enough to hold the cams in operation. I know that Malcolm used loctite, it's just that I'm a bit cautious about using it on rotating parts.
> 
> Paul.



Me too. I come from WW ll  when Loctite if on hand would have been scoffed by
my neighbourhood maestros who believed in keys,dowel pins etc.:rant:

Will watch and see. No offence. Gus is too conservative. And fear of the unknown.But I am open minded on Loctite.

7.45am Singapore time.Will clock in at 8:00 am to work on Con-Rod.Will do it smarter this time. The last two Con-Rods barely passed Q.C. for Webbie and Rupnow H&M Engines.:hDe:


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## Brian Rupnow (Jun 8, 2014)

Properly applied and cured Loctite is very powerful stuff. Am I confident of its holding ability in this condition?--Hell No!!! But then again, maybe it will work fine. Any problems I have had with Loctite not holding in the past was more a case of my impatience than of Loctites holding ability. I cleaned both parts to be Loctited with "hot" paint thinners, which will degrease anything. I sanded the shaft with light sandpaper to abrade it to give something for the Loctite to grip. I set the Loctited parts up under a 60 watt lightbulb for 12 hours to speed up the curing time. I am a bit concerned about the strength of the valve springs I used---(0.025" diameter wire). This is a case of being between Devil and deep blue sea. A good strong spring will help avoid valve leakage problems. However, that same strength may make the Loctite let go. i will try it and see. If (worst case scenario) the Loctite lets go, I will carbide a 1mm hole through the shaft and the cam shoulder and put in a dowel pin.


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## Brian Rupnow (Jun 9, 2014)

Here we have a finished cam shaft. It turned out fairly decent, and I think I have the lobes at the required 102.5 degrees separation as recommended by Malcolm. I have never Loctited cams to the camshaft before, but I guess there is a first time for everything.


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## Brian Rupnow (Jun 9, 2014)

We all know that there are two kinds of "close".. There is "Hmm--that's close" and there is "Oh My God---That's close!!!!". This engine definitely falls into the second category.  Things are tighter than a mouse's ear where the push-rod goes past that intake manifold.  However--after a full days "frigging" The cam shaft does indeed do its thing, the rocker arms rock, and the valves open and close. I had to put a .025" spacer under the rocker arm support bracket in order to get my rocker arms setting level.---I must have made the valves a tad longer than the original plans called for.


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## Brian Rupnow (Jun 9, 2014)

I may have over-reached myself with the design of this gearcase. It surely does look pretty, but it is going to be a monster to make with a manual mill. I have sat here tonight for two hours on the computer, mapping out the steps I will take to make it. I have a plan, at any rate. I REALLY wish I had brass to make it from, but I don't---However I have an abundance of bronze. I want it to be colored metal to match the bronze flywheel, and bronze will be a perfect color match at any rate. i will post progress as I move through the steps to machine it---if nothing else, it will provide some comic relief!!!


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## Brian Rupnow (Jun 10, 2014)

The gearcase journey begins here. I have a drawing, but ultimately the outline of the gearcase has to match the outline of the part it mates with, which supports one of the main bearings. For some reason, and I'm sure it's my machining, the parts I make from drawings always "drift" a bit from the drawing. Not in critical areas that must be precise, but in things like flanges that kind of hang out in the air and don't perform any critical function, other than a place to put bolts in. In cases like this where it must be an exact match, I find it much safer to trace around the outline of the existing part rather than rely on the drawing. Strangely enough, this time the positioning of the counterbore that covers the gears isn't all that critical, as I have allowed 0.060" radial clearance around the major diameters of the gears for clearance. These will start out as 3 separate counterbores, which will then then be connected by tangent lines and then tha area enclosed by the tangent lines will also be removed to from the gear cavity. You can see that the face of the bronze piece I am working from has suffered the indignity of having some fool strike an arc across the face of it ("twasn't me) --but thats okay. Most of it will be milled away before I get finished.


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## Brian Rupnow (Jun 10, 2014)

This went far easier than I had anticipated. I trimmed the piece of plate to finished width with bandsaw and mill, set it up in my vice on parallels to give a bit of backside clearance, then drilled and reamed three 3/16" holes completely through the part. These holes will get plugged eventually. I need then to register when I flip the plate over to mill the material away around the flange on the other side of the plate. I opened out the two smaller holes with a 3/4" endmill to the required depth, and used a 1" end mill (my largest) to open out the large hole to full depth.  then I used the boring tool to open the big hole out to a large enough diameter to clear the teeth on the camshaft gear. Then i was able to advance the table in the X axis and keep taking cuts with the boring head until the resuling slot intersected with the teo smaller holes. I then re-registered the spindle over the two smaller holes (using a piece of 3/16" cold rolled in the drill chuck to find the center of the 3/16" reamed holes, and finished boring the small holes out to the required 0.834" diameter. Now all I have to do is set the part up in my swivel based vice to clear a small bit of material from the right hand side of the hole. I am always a bit worried on a piece like this that I may be making it backwards (I've done that before) but a trial fit on the engine shows that all is well. Now on to my next step!!


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## Brian Rupnow (Jun 10, 2014)

A bit of "profiling" with the bandsaw and my giant vertical 6" belt sander brings the outer perimeter "to the line".


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## Brian Rupnow (Jun 10, 2014)

I set my Vernier caliper to the length of flange I wanted, and scribed a line all around the perimeter of the gearcase. Then it was a simple matter to set the gearcase on edge in the milling vice and mill to the line, all around, leaving the thickness of flange I wanted undisturbed. Then 10 minutes of file work and a bit of time with the polishing wheel, and it's finished. I am super pleased with the way it turned out. Tomorrow I will machine a couple of brass button head plugs and Loctite them into the two remaining holes. while I had the polishing buffs out, I gave the flywheel a little shine also.


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## Brian Rupnow (Jun 10, 2014)

Thanks for all the nice comments, guys. You know, after all my moaning about wanting to make that part out of brass, I'm pretty sure it WAS brass. I bought it out of the bronze rack at my suppliers, but I think they had put it there by mistake. It machined like brass. It polished like brass. It doesn't have that reddish tinge to it that the flywheel does. (I know that the flywheel is bronze.) All I have left to make now is the sump and the piston rings. (I made the ignition cam after I posted the last pictures).


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## Swifty (Jun 10, 2014)

Looking great Brian, I'm always amazed at the speed that you can produce these engines.

Paul.


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## Brian Rupnow (Jun 11, 2014)

A lot of what I did today doesn't show. This morning I made the sump, drilled and tapped the bottom of the crankcase and bolted the sump on. The con-rod big end was a bit tight on the journal, so I applied lots of oil and ran this engine in with a belt drive from an electric motor. I kind of made up my exhaust as I went along, but I like it. Tomorrow morning I will mount the ignition points that are laying in the foreground, and then I will make the piston rings.


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## doubletop (Jun 12, 2014)

Looking great Brian


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## Brian Rupnow (Jun 12, 2014)

So there we have it folks. All finished except for the rings. The silicone gasket goo is in place, the valve timing is done, all of the electrics are on and the ignition timing has been set.--Rings tomorrow!!!


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## gus (Jun 13, 2014)

Hi Brian,

This is fantastic. You beat Paul and Gus. I have about 2--3 weeks to go but I am not rushing. Sort of ''Go easy''.  Had to make a new 
con-rod. Some how the big end needle bearing got mis-aligned. Cranking thru 360 degrees from smooth to very difficult.
Please post video.Brian should have no problem getting this engine started and spinning.


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## Brian Rupnow (Jun 13, 2014)

I lied!!--Well, no, I didn't really lie.---This little engine has such a small base that I was afraid it was going to fall over and get damaged. ---And seeing that I have the largest supply of bronze in the free world, I spent this morning carving out a base from bronze and adding a gas tank which I stole from one of my other engines. NOW I'm ready to make the rings.---I promise!!!


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## cfellows (Jun 13, 2014)

Looks real good, Brian.  I just ordered some O-Rings for my Oil Field Engine.  Had to buy 50 of them, but the price was reasonable.  I love McMaster Carr!

 Chuck


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## Brian Rupnow (Jun 13, 2014)

Here we are at step #1 of piston ring making. I have had advice from two well informed sources, one who says turn the ring about .004" over the cylinder diameter, and one who insists it be exactly at the cylinder diameter. I don't think it matters a hoot, because these rings are going to get split, then expanded, then heat treated, then have the ends filed to give a .003" gap when setting in the cylinder. I hedged my bets and made the outer diameter .002 larger than the cylinder diameter. 
I turned the inner diameter to be a total of .080" less than the outer diameter, which is as close as Damn is to swearing to 1 millimeter ring thickness. I have taken the first cut with my 1.5mm parting tool to square up the end of the blank before I start parting off rings. Tomorrow morning I will mount the dial indicator on my cradle stop, pull the piston out of the engine to have it on hand, and part off as many rings as I can get, after checking to confirm that the rings are a nice sliding fit into the ring grooves in the piston.


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## Brian Rupnow (Jun 14, 2014)

This morning I parted off the rings. My calculations which appear on the paper which the rings are setting on show that I needed a ring .051" wide to suit the .052" groove in the piston. I used the same cut off tool to part off the rings as I did for cutting the grooves in the piston. The first ring parted off beautifully, but then I spent 10 minutes rubbing alternate sides on a piece of 220 grit emery  paper spread out on my bandsaw table (flat surface) to get it down to a comfortable fit into the ring groove. On the next ring I set the parting off tool over only .098" and the rings were a much better fit into the ring grooves. I gave each ring 20 "laps" on the 220 grit emery paper per side. This is a simple matter of laying the ring flat on the emery paper, putting two fingers on it to spread the pressure evenly, and then making about a 2" circular path with the face of the ring against the paper.


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## Brian Rupnow (Jun 14, 2014)

Since I didn't have an M3 taper to use in splitting the rings, as suggested by Malcolm Stride, I used the "Vice method".  This one is pretty simple. You grip the portion you want to break in the vice jaws, close to the center of the ring, but leave the part you want to remain unbroken below the jaws so it is not gripped. A quick wiggle at finger pressure (these unheat-treated rings are quite brittle) and "snap"--you are done. I split all of these rings in less than 5 minutes and never broke any of them in half. Now I have to wait for the stores to open and go in search of a "fine diamond file".


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## Brian Rupnow (Jun 14, 2014)

So here's the deal---I made seven rings. One broke just from handling it--no good reason that I could see. i made a fixture to heat treat the, and made the diameter of the fixture where the rings fit onto 1 mm or 0.040" larger than the inside diameter of the rings. I made the fixture such a length that when 6 rings were on it, the last ring set about .025" "proud" from the end, so that when the cap plate was screwed on it would squeeze all of the rings together. I found that when the rings are stretched over the fixture, the gap becomes about 0.100" or 2.5mm. I think I could probably get away without the 2.5mm wedge of material between the ring ends, but just for safetys sake I will put it in there---I don't want to have to make more rings. The very top ring in the stack broke as I was stretching it over the fixture, but I needed the height of that ring to make my fixture work, so I put the gap in that last ring next to the squeeze plate on the opposite side to all the rest. Now, the idea is to heat this stack of compressed rings to cherry red and hold it there for 10 minutes, then let it cool naturally. This is supposed to "set" the rings.


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## Brian Rupnow (Jun 14, 2014)

I'm pooched!!! Got all ready to rock and roll, and ran out of oxygen!! Called my welding gas supplier and they are closed until Monday. Propane torch doesn't get hot enough. Will continue this saga Monday.---Brian


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## Swifty (Jun 14, 2014)

It's all looking great Brian, I think the benefit of breaking the rings on a taper is that they naturally want to crack on any weakness, giving the strongest rings possible. I don't have an oxy / acetylene set, I just used my Mapp torch to heat them up, I held the heat for about 5 - 6 minutes before I got tired of that, appeared to work well.

I had the same problem parting off as you did, the first ring cut on theoretical size was a bit too wide, so a minor adjustment fixed that. I recall reading on this forum somewhere, that a steel plate with a recess milled or turned to the correct thickness of the finished rings is a great way to hold the rings when rubbing on emery paper, you can't overshoot the size as the plate stops you. But we are only after a couple of rings, so the finger method is fine.

Paul.


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## doubletop (Jun 14, 2014)

Brian Rupnow said:


> Propane torch doesn't get hot enough. Will continue this saga Monday.---Brian



 I'm surprised it doesn't  Pete


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## Brian Rupnow (Jun 14, 2014)

I held the propane torch on the stack of rings for two minutes and nothing had started to turn red. I have never been able to do anything very exciting with a propane torch, other than soft solder copper waterpipes together. If the stack doesn't get cherry red, then the heat treat won't work. I kind of question Malcolm Stride's suggested "10 minutes" but obviously it worked for him. I just naturally go to the oxy acetylene rig for anything requiring real heat. I even silver solder with the oxy acetylene torch.---Brian


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## Jasonb (Jun 15, 2014)

Its not the propane that is the problem, more likely the size of your burner, my 1" dia burner would do it no problem but if I put the fine 3/8" dia burner on the same gas bottle/torch I would be there all day its all to do with the KW rating of the burner.

Reducing the bulk of your holding fixture would also help.

Do make sure you keep the Oxy torch moving to heat the rings evenly, in the past I have got the heat too much in one spot with the propane while trying to take a photo at the same time and all the change in shape of the ring happened in the hot part so they did not fit evenly when put in the cylinder, like trying to fit an egg into a round hole


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## Brian Rupnow (Jun 15, 2014)

Due to the almost frantic lack of clearance where the valve pushrods pass the manifold bolts, I came up with a plan for a "stepped" pushrod, which would be 0.100" diameter in the lower half and .062" in the upper half that runs past the intake and exhaust bolts. This caused a certain amount of head slapping in my shop yesterday. I actually found a piece of .093" rod, and set up to drill the 1/16" diameter x 5/16" deep holes in it, as shown in the drawing. My smallest center drill did make a small center, but none of my drills would even touch the stuff. Complaining bitterly to my wife about how dull all my drills had become, I went up to the hardware store and bought two new 1/16" drills.---and they wouldn't touch it!!! Then it occurred to me to do a bit of a file test. That rod was a piece of music wire, and was harder than the devils horn. I can't even remember what I had bought it for. A small hunt around my shop yielded a piece of 1/8" cold rolled, and it drilled just fine, the two part pushrods were made up and silver soldered together with no farther mishap.


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## Brian Rupnow (Jun 15, 2014)

Here is a quick question for the other engine building guru's. When I built the cast iron cylinder for this engine, I lapped it to size internally, using a lap and 600 grit lapping paste. This removed a tight spot which was a result of reaming, and left the cylinder very smooth on the inside bore---which would be perfect for Viton rings. However, since I am going to attempt to run cast iron rings, should I rum my 3 stone brake hone though the cylinder a couple of times to leave a cross hatch pattern on the walls. I have heard that the micro grooves left by this cross hatch pattern acts to retain oil for lubrication of the rings, and helps the rings to "seat" much more rapidly in the cylinder.---Brian


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## Brian Rupnow (Jun 15, 2014)

Topct and J.R. Williams--I do read every comment and observation made, and I appreciate that you take the time to comment and/or ask questions. You both asked about an oil filler/breather tube and a dipstick. I hadn't even given much consideration to it at the time, but I spent this afternoon hashing something out. There will not be a dipstick. There is however an oil filler/breather tube, and a "check oil level" tube. The 7/16" hex nut is not part of anything--it was just used as a driver. There will be a cap screwed onto the "check oil level" tube. There will also be a vented cap screwed onto the oil filler/breather tube. Here is how it goes--I checked this afternoon, and it takes about 3/4 of an ounce to fill the oil sump, up to the level of the tube screwed into the side of the crankcase. When the oil is at that level, the rod cap will dip into the oil with each revolution of the crank. So---I pour an ounce of oil into the filler breather tube. Then I unscrew the cap from the "check oil level" tube, and let anything run out that will run out. This assures me that there is a sufficient level of oil in the engine.---Brian


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## doubletop (Jun 16, 2014)

Brian  I just used 1/16" music wire for my push rods. They just sit in the dimple formed by the drill bit when the cam followers were made. They don't jump out, the engine vibration naturally keeps them in the centre of the follower I'm sure thats to Malcolms design  Pete


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## Brian Rupnow (Jun 16, 2014)

The empty oxygen tank has been replaced, and the rings heat treated. They are now cooling out in my main garage. One last word about the oil filler/breather system and then we will leave it forever. The crankcase is theoretically "air tight". That being the case, it would be almost impossible to pour oil down that long filler tube into the engine without a resulting air-lock, and no flow. On top of the crankcase, which currently has the cylinder removed, you will see the head of a #4-40 socket head capscrew, with a rather smudged black arrow pointing at it. That is my vent--the hole is tapped right through into the crankcase. When filling with oil, that screw will be removed to prevent an air-lock, then it will be re-inserted.


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## Brian Rupnow (Jun 16, 2014)

Based on many years of hot-rod engine building experience, I simply couldn't bring myself to install new cast iron rings into a cylinder with extremely smooth walls from the lapping process. While my heat treated rings are cooling off I pulled the head off the cylinder and gave it a few passes with the 3 stone brake-shoe honing tool. This creates cross hatched micro grooves in the cylinder wall to retain some oil for piston and ring lubrication, and is supposed to help new rings "seat" much better in the cylinder to give good compression.


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## Brian Rupnow (Jun 16, 2014)

My first attempt at ring making was a FAIL!!! I must have got them too hot. They were fused together at the face on one side and when I went to separate them they broke.


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## Brian Rupnow (Jun 16, 2014)

If at first you don't succeed---Make 12 more rings and try again. BUT--If I don't get two good rings out of this bunch, we are going with Viton!!! I am going to take some of the mass out of my heat treat fixture, and not get quite so close with the torch on this next bunch!!


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## Swifty (Jun 16, 2014)

The base of my heat treatment fixture is about half the thickness of yours in the original photo. Only having a Mapp torch, I did not want to heat up too much waste material. Maybe you got the lot too hot with the oxy/acetylene.

Paul.


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## Brian Rupnow (Jun 16, 2014)

HAH!!!! Much better luck the second time around. I took about half the material out of my heat treat fixture, and this time I didn't let the torch blow directly on the rings---Just heated the one end of the fixture to cherry red and let the heat soak through to the rings. Notice that they all "took a set" and now have the recommended 2.5mm gap . This is GOOD!!! Swifty-- the edges are still pretty damn sharp. How did you deal with that issue on your rings? I bought a set of 4 diamond files, but they will only be good to square the ends of the rings at the gap.


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## Swifty (Jun 16, 2014)

Brian, I used a half round needle file on the inside of the rings, and a flat needle file on the outside corners to put a slight chamfer on them before treating them. I don't know why you need diamond files, although it's called heat treating the rings, they don't harden, it just sets the open gap. I held the finished rings in a toolmakers vice and gave the gap ends a few strokes with a file, then put the ring in the cylinder to check that I had 0.1mm closed gap.

Paul.


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## gus (Jun 16, 2014)

Swifty said:


> The base of my heat treatment fixture is about half the thickness of yours in the original photo. Only having a Mapp torch, I did not want to heat up too much waste material. Maybe you got the lot too hot with the oxy/acetylene.
> 
> Paul.




Are you using single burner torch or two burner torch ?? I will using Mapp Gas
Torch.


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## Swifty (Jun 16, 2014)

gus said:


> Are you using single burner torch or two burner torch ?? I will using Mapp Gas
> Torch.



I only have a single burner torch, used a couple of fire bricks to contain the heat. The Mapp burners are great.

Paul.


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## Brian Rupnow (Jun 16, 2014)

Well, the rings are in. The motor is all buttoned up and filled to the proper level with oil. I have taken the flywheel off and put that old 8" pulley on, and I am going to let the red electric motor drive it for about 3 hours to seat the rings. The engine is turning over at about 800 RPM.  This "running in" step may not be absolutely necessary, but it shouldn't hurt anything, and if it helps, then I should be ready to fire this engine up sometime tomorrow. While I had the cylinder off the engine with the head still attached to it, I tried the old "Put your mouth over the open end of the cylinder and blow your guts out!!!" method of checking the valves for leaks. The intake had no leaks at all. The exhaust valve did and didn't depending on how the valve was rotated. One thing about steel valves in brass or bronze seats---the more they run, the better they seal. So---the running in should/may help totally seat the exhaust valve. I have the pushrods in and the valves and cam are functioning as the engine turns over.


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## Brian Rupnow (Jun 17, 2014)

Engine has just been "run in" for 3 hours, driven by an electric motor, in an attempt to "seat" the new cast iron rings. After tearing down the "run in" set-up, engine has very little compression. I put a spoonfull of heavy gear oil down the sparkplug hole, and there was very little difference in compression. I am not in a rush to start tearing things apart. I think my next move will be to hook up the gas tank and ignition and try to start it. You never know with these little engines--sometimes if you can get them to fire and run at all under there own power, the compression will come up a lot after they run for 10 minutes.---Must say though, that I am disappointed with preliminary  results!!!


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## Brian Rupnow (Jun 17, 2014)

Well--For the moment, I am snookered. I hooked everything up on the engine and cranked it numerous times with my variable speed electric drill, but other than a couple of smoke rings, it was a no run situation. I checked my valve lash and the lash is okay--the valves are closing completely. I even got my can of ether "Quick Start" out, and gave the carb a shot while cranking the engine over, but no joy. I have lots of spark, and its coming at the correct time. The valve timing sequence is correct. I just pulled the cylinder off and the rings LOOK okay, but there was very very little compression, and the heavy oil down the sparkplug hole didn't make any difference to the compression when turning the engine over by hand. Once again, I held my lips over the open end of the cylinder and blew until I thought I might pass out, and there is absolutely no leaks at the valves unless I depress them by hand. The ring grooves in the piston are actually deeper than they should have been, but I don't think that would prevent the rings from sealing at any rate. The grooves are however, just about the perfect depth for a Viton o-ring, although they are a bit too narrow. Right now I am approaching burn out on this engine. I think perhaps I will pull the piston out and widen the grooves enough to accept a Viton 1/16" cross section o-ring, and see what happens to the compression with a pair of Viton rings.


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## 74Sprint (Jun 17, 2014)

What is your ring end gap when the ring is squarely in the bore? Also are you staggering the gaps?

Ray


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## Brian Rupnow (Jun 17, 2014)

74Sprint said:


> What is your ring end gap when the ring is squarely in the bore? Also are you staggering the gaps?
> 
> Ray


Working ring gap is 0.003". Ring gaps are set opposite to each other.


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## 74Sprint (Jun 17, 2014)

Ok back off the rockers or remove the push rods. Next pull the sparkplug, put the piston at bottom dead center, use a different sparkplug and put it in with generous oil on the threads. Next try to crank the engine by hand and see if you get good compression and no bubbles around the sparkplug. This process has always helped me narrow things down.

Ray


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## Brian Rupnow (Jun 17, 2014)

As of this moment I have modified the ring grooves to accept Viton o-rings. I am off to Hercules o-ring at the other end of Barrie to pick up the rings.---Brian


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## johnny1320 (Jun 17, 2014)

Just for kicks Brian put the rings in the bore and shine a light behind them and see if they are sealing all the why around.


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## Brian Rupnow (Jun 17, 2014)

Too late Johnny---The piston has now been modified for 1/16" cross section Viton o-rings. the groove now measures .085" wide x exactly 1/16" deep. One ring is on the piston, one is laying in the foreground. Also in the picture is my "handle" which I can fit to the piston (it has a  hole in the end of it that the wrist or "gudgeon" pin fits into). With the handle I am able to insert the piston into the cylinder/head assembly and work it back and forth by hand to see if I can feel any "compression" or suction. With the cast iron rings I couldn't feel anything. With  2 Viton o-rings there was too much friction. With one Viton o-ring there was both compression and suction when I worked the piston back and forth in the cylinder. I am going out now to the main garage and reassemble the engine with one Viton o-ring on the piston and try it. All of you anti-Viton scare mongers---don't bother posting all of your dire warnings about Viton.  I've heard it all and I'm not interested!!!


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## johnny1320 (Jun 17, 2014)

I was just courious weather or not you could see light, I wasn't sugesting not to go with "o" rings. Looking forward to noise.


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## Swifty (Jun 17, 2014)

That's a shame Brian, after all that work on those piston rings. I assembled my piston and rings yesterday and inserted it into the cylinder, with just a small amount of oil wiped on the cylinder, I have good suction when I place the palm of my hand over the top of the cylinder.

Paul.


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## Brian Rupnow (Jun 17, 2014)

Swifty--Nothing really hurt here, except maybe my pride----I spent $5.00 for a 3" length of grey cast iron for my ring making experiment. When I get to this point, an engine all finished but doesn't run for some compression related issue, its easier for me to go directly to Viton rings that just about any other possible solution. The engine now has compression and is firing along with the electric drill, the cylinders is getting hot and I see smoke coming out the exhaust with every "pop", although I haven't had a sustained, unassisted run yet. My theory is that if I can get the engine running and firing regularly, it will seal up the valves completely after it runs a bit. Its a couple of hours work to make a new piston with the correct depth of grooves, and I have a lifetime supply of rings now. So---Get the engine running, then after I am satisfied with its running, put in a new piston with cast iron rings and try again when I am sure it is not some other issue keeping the engine from running.


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## Brian Rupnow (Jun 17, 2014)

Johnny--I apologize if my answer sounded kind of ignorant. I didn't intend it to be. It's been kind of a wild and crazy afternoon here, and the o-ring place is about as far from here as it could possibly be and still qualify as being in Barrie. I am posting all of this stuff in "real time" and sometimes I have things changed before I see a post and can respond to it. Your idea certainly has merit, and I do intend to pursue this cast iron ring business, once I get the engine to actually run.---Brian


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## Brian Rupnow (Jun 17, 2014)

That's all folks!!!--for today anyways. If I do any more today, I'm going to be too stoked to sleep tonight. (If I'm not already.) I have progressed to the point of short duration runs, but none long enough to make me run for the video camera. I am down to that very fine balancing point between fuel mixture and ignition timing. The Chuck Fellows carburetor that I built has an extremely small range between too much gas and no gas at all. It doesn't have a sewing needle for the main (only) mixture control, but instead has a home made needle with a long taper made on my lathe. I may have to switch it out for one of my store bought model airplane carbs until I get good sustained runs. (They have a much wider range of mixture, because of their construction.)  Thanks for watching and commenting today.---Brian


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## gus (Jun 17, 2014)

Brian Rupnow said:


> Well--For the moment, I am snookered. I hooked everything up on the engine and cranked it numerous times with my variable speed electric drill, but other than a couple of smoke rings, it was a no run situation. I checked my valve lash and the lash is okay--the valves are closing completely. I even got my can of ether "Quick Start" out, and gave the carb a shot while cranking the engine over, but no joy. I have lots of spark, and its coming at the correct time. The valve timing sequence is correct. I just pulled the cylinder off and the rings LOOK okay, but there was very very little compression, and the heavy oil down the sparkplug hole didn't make any difference to the compression when turning the engine over by hand. Once again, I held my lips over the open end of the cylinder and blew until I thought I might pass out, and there is absolutely no leaks at the valves unless I depress them by hand. The ring grooves in the piston are actually deeper than they should have been, but I don't think that would prevent the rings from sealing at any rate. The grooves are however, just about the perfect depth for a Viton o-ring, although they are a bit too narrow. Right now I am approaching burn out on this engine. I think perhaps I will pull the piston out and widen the grooves enough to accept a Viton 1/16" cross section o-ring, and see what happens to the compression with a pair of Viton rings.



Hi Brian,
Take care as its only a hobby. Burnt-out is no fun, The 1997 burnt-out took me two months to  but not fully till another 4 months. This after successful design and construction of a fully automatic non-contact roller conveyor lines to transfer finished compressor packages to main warehouse.


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## gus (Jun 17, 2014)

Brian Rupnow said:


> That's all folks!!!--for today anyways. If I do any more today, I'm going to be too stoked to sleep tonight. (If I'm not already.) I have progressed to the point of short duration runs, but none long enough to make me run for the video camera. I am down to that very fine balancing point between fuel mixture and ignition timing. The Chuck Fellows carburetor that I built has an extremely small range between too much gas and no gas at all. It doesn't have a sewing needle for the main (only) mixture control, but instead has a home made needle with a long taper made on my lathe. I may have to switch it out for one of my store bought model airplane carbs until I get good sustained runs. (They have a much wider range of mixture, because of their construction.)  Thanks for watching and commenting today.---Brian




Hurray!! You got putting away. th_wavCome back in three days,she will run and purr like a cat. The Webster Engine did this to poor Gus. Just very slight turn of the fuel jet and she ran.


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## johnny1320 (Jun 17, 2014)

I can't get over how fast you build these engines Brian, looking forward to a video


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## GailInNM (Jun 17, 2014)

Brian,
I think I know way your rings did not work.



Brian Rupnow said:


> .....I made a fixture to heat treat the, and made the diameter of the fixture where the rings fit onto 1 mm or 0.040" larger than the inside diameter of the rings.  ....... I found that when the rings are stretched over the fixture, the gap becomes about 0.100".....



With your fixture the rings are expanded in a radial manner, that is they are expanded into a circle around the fixture.  This would be no different than just cutting them oversize and removing material in the gap.  Since they are formed to a circle then when compressed they are no longer a circle.

The mandrel should not do more than touch the split rings. A bit under is OK.  Then when the ring is spread to fit over the spacer for the ends they will only touch at the point opposite the spacer and the ends at the spacer. You are expanding on a tangent and not a radius. At this point they are no longer a circle. After heat treating they are not a circle. But, when the gap is closed they will be very close to a circle.  It will not be a perfect circle but it is close enough for our purposes.  

The math behind all of this is daunting but you can do a simple demonstration that may help you visualize it.  Wind a couple of turns of bare straightened electrical wire around a round rod.  Number 14 wire around a 1 inch diameter rod shouldl be fine.  Cut a 1 turn section out of it. Now expand the diameter by spreading the ends.  You will see that the wire bends differently all along the half circle to the point opposite the split.

There is no simple way to make a perfect ring in the home shop but the tangent expansion is one of the closest ways that is practical for us.

Gail in NM
Edit: A little bit of reading that can explain it better than I can"
http://www.modelenginenews.org/techniques/piston_rings.html
http://jerry-howell.com/PistonRings.html


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## Brian Rupnow (Jun 18, 2014)

Gail--I have 7 rings left un-heattreated. I will try this method on a couple and see what happens. Thank you for looking and for the advice.---Brian


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## Brian Rupnow (Jun 18, 2014)

What to do---what to do----I am at that juncture I always seem to arrive at when trying to get one of these engines to run on it's own. I put the model airplane carburetor on. Results are about the same as with the Chuck Fellows carburetor. This probably means that it wasn't the fault of the Chuck Fellows carburetor after all. Engine will start and run along with drill if I choke it by putting my finger briefly over the air intake.-Trouble is, it will only run until this extra rich charge of fuel is burned, then it quits firing. At this point, logic would dictate that I should open the needle valve just a touch more to give the extra fuel, and the engine should keep running---only it doesn't. It floods. I think I actually had better sustained firing with Chuck's carburetor. If we take compression out of the equation, there are only three things involved.--Carburetor setting, ignition timing, or valve timing. I hate to think it would be valve timing, because that involves taking the points and ignition cam and fancy brass gear cover off to change it. I have tried two different carburetors that performed flawlessly on my other i.c. engines. --Maybe that knocks it down to only two variables, ignition and valve timing. Maybe I will pull the remaining hair out of my head---or maybe----


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## picks27t (Jun 18, 2014)

Brian Rupnow said:


> What to do---what to do----I am at that juncture I always seem to arrive at when trying to get one of these engines to run on it's own. I put the model airplane carburetor on. Results are about the same as with the Chuck Fellows carburetor. This probably means that it wasn't the fault of the Chuck Fellows carburetor after all. Engine will start and run along with drill if I choke it by putting my finger briefly over the air intake.-Trouble is, it will only run until this extra rich charge of fuel is burned, then it quits firing. At this point, logic would dictate that I should open the needle valve just a touch more to give the extra fuel, and the engine should keep running---only it doesn't. It floods. I think I actually had better sustained firing with Chuck's carburetor. If we take compression out of the equation, there are only three things involved.--Carburetor setting, ignition timing, or valve timing. I hate to think it would be valve timing, because that involves taking the points and ignition cam and fancy brass gear cover off to change it. I have tried two different carburetors that performed flawlessly on my other i.c. engines. --Maybe that knocks it down to only two variables, ignition and valve timing. Maybe I will pull the remaining hair out of my head---or maybe----





How about trying some glow fule anh


Sent from my iPhone using Model Engines


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## picks27t (Jun 18, 2014)

And glow plug i have got some running like that just to check it out 


Sent from my iPhone using Model Engines


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## johnny1320 (Jun 18, 2014)

Put a degree wheel on her and check the cam timing.


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## Brian Rupnow (Jun 18, 2014)

I put the Chuck Fellows carb back on (I lied about the needle---had it confused with the George Britnell carb clone that I built--The Fellows carb does have a nice tapered needle.) I monkeyed with the ignition timing and got a couple of good sustained runs. I could have ran and got the video camera, but the sun is down now and there isn't that much light out in my main garage. My timing gears are making a terrible racket--sounds like somebody torturing a duck!!! I may have to put a mark on the cam shaft and the ignition cam to be able to re-set them to this setting, and pull the gear cover off to see what in heck is going on with the gears. I never had gears make a racket like that before, but I have never used a jockey gear between the crank and cam gear before, so I expect it may have something to do with that. Since I have to pull the gear cover, I will set up a degree wheel and a pointer and check the valve timing while I have things apart.


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## Brian Rupnow (Jun 19, 2014)

Back to work on the engine this morning. I have dismounted it from the bronze sub base and brought it back into the office/machine shop. The engine has developed amazing compression after all the short runs it had yesterday. I pulled the gear cover off to see why my timing gears are squawking like ruptured ducks, but there is no reason immediately visible. I may take the cowards way out and coat them with 600 grit lapping paste and run them for 25 minutes to see if it quiets them down any.--That has worked for me before.The jockey gear floats on its pinion--it is supposed to. However it also has a certain amount of "float" longitudinally as well. I may see about some form of spacer to prevent that axial movement. I am going to have to do some studying on this degree wheel business as outlined by Malcolm Stride to set the valve timing. I don't fully understand it, as I have always set the gear timing "by eye".


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## Brian Rupnow (Jun 19, 2014)

This is a quick pic of "running in" the spur gears with some 600 grit lapping paste on the teeth of the gears. The black o-ring drive belt is driving the engine crankshaft via the mill quill mounted pulley. I will let it run for about half an hour like this, and hopefully get the noise out of my gears.


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## Brian Rupnow (Jun 19, 2014)

I had expected that the lubricating oil from the sump would find its way out into the gearcase to lubricate the gears. Not so---When I pulled the gear cover off, those gears were dry as a bone. I will pack the gearcase with grease before I reassemble things.


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## Brian Rupnow (Jun 19, 2014)

It only took about 10 minutes of running until all the squawk was gone from the gears. However, I have developed a theory as I have been doing this. The ignition cam and the cam gear are both cantilevered out bast the support bearing on that side, with the ignition cam being farthest out. The spring in the ignition points is very strong, and the shaft which is only 4 mm diameter may be deflecting when the cam has to compress the spring which holds the points shut, to open them. If so, the shaft could be deflecting, which would change the mesh of the large cam gear and create the noise. I may have to put an outboard bearing on the gear cover to prevent the shaft deflection---Don't know yet!!!


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## Brian Rupnow (Jun 20, 2014)

HAPPY DAYS ARE HERE AGAIN---YES!!!! We have a runner. I tried every trick I know of with both the Chuck Fellows carb and the model airplane carb and no joy!!!--Then I switched over to my George Britnell Clone carb and almost immediately had a runner. This engine has been a real oinker to get running, but I feel much better about the world right now!!!---Brian


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## Swifty (Jun 20, 2014)

Very nice Brian, now you can think about your next project

Paul.


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## petertha (Jun 20, 2014)

Brian Rupnow said:


> ..with both the Chuck Fellows carb and the model airplane carb and no joy!!!--Then I switched over to my George Britnell Clone carb and almost immediately had a runner.



Congrats, purring like a kitten. So what's the moral of the story? Are all 3 carbs similarly sized or George carb is the sweet spot? Or different venturi shape/action? Or relative positioning? Mixture control? etc etc


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## Brian Rupnow (Jun 20, 2014)

There is no logical reason for it to run on one carburetor and not the others. All three of those carbs are interchangeable on my other internal combustion engines, and they all work equally well. There are other things at work here that I don't fully understand yet. This morning the engine had incredible compression. After that one good run where I took the video, it wouldn't start and I had no compression. Obviously something has changed, but I'm not sure what, and I haven't felt like playing with it this afternoon. I don't think anything is terribly wrong, but there are some transients at work here that I have to figure out, and it should run on any of the carburetors.----Brian


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## Brian Rupnow (Jun 21, 2014)

We had both grand-daughters sleep over last night, as today we have tickets for the live theater version of Peter Pan. I am up early, just beginning a run of diagnostics on the engine. First though, I thought a couple of updates were in order. The running in of the gears with 600 grit compound, as outlined earlier has silenced them completely--no more "stepped on duck" noises from the engine as it rotates. The gearcase was filled with grease, as none of the sump oil was making it out to lubricate the gears. I may have gotten a bit too exuberant with the amount of grease I packed in, because for the first few runs I had grease oozing out around the camshaft where it exits the gearcase, as there is no seal there. I was concerned about deflection of the end of the camshaft, because the spring in the ignition points is quite powerful, and the ignition cam is cantilevered a long ways out past the bearing. I solved that issue by making a new ignition cam with an extended 5/16" (about 8mm) shoulder on it, and made a new brass bearing to capture and support it which bolts to the outside of the gearcase. This has completely solved the deflection problem. The deflection problem may also have been part of the reason for my squawky gears, I'm not certain. I am now about to pull the cylinder and head off and try to figure out where my compression has gone to.


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## Brian Rupnow (Jun 21, 2014)

After a quick disassembly and check, there doesn't seem to be any leakage at the valves, as I had feared. The o-ring may have been worn a bit, because, as you remember, I had cross hatched the inside of the cylinder with my brake hone in preparation for the cast iron valves. This will wear the outside of a Viton o-ring away very quickly until the cross hatching on the cylinder wall is polished out by the action of the ring rubbing on it. I seem to have restored my compression enough to get a "bounce back" when I give the flywheel a flip by hand, so I may (cross my fingers)  have solved the problem. I might get a chance to find out later today.


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## doubletop (Jun 21, 2014)

Great job in getting it to run but Deja Vu !! Your starting, carb and compression problems just about exactly reflect my experience with both engines (Bobcat and Lynx). You experience with other engines helped you to work through it but I was a first timer so went down a fe blind alleys and loops before I got mine running.  Unfortunately I'm unable to view the video as I'm running Firefox and the No script add-on. After allowing links to 20+ other sites from the Photobucket site to the point I get a &quot;do you really want to do this&quot; message so I can't get the video to run. (have you put it in YouTube?)  What does it rev like? Any idea about the max RPM you've achieved?   Pete    (And for some reason running Firefox on Linux removes all the CR/LF's from the text)


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## Brian Rupnow (Jun 21, 2014)

Doubletop--Here is the link to the same video on Youtube. Note the vapour shooting out the intake barrel of the carburetor. I think that the valve timing is a bit too radical for a single cylinder engine, but I'm not really sure. My intake valve is not leaking, and the lash is set correctly. Does your engione do that?---Brian
[ame]https://www.youtube.com/watch?v=6VBaEu9Ivdo&feature=youtu.be[/ame]


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## Brian Rupnow (Jun 21, 2014)

Has anyone ever seen this engine built to its original Jaguar single cylinder configuration? I have searched the internet trying to find a video of it, and I can not find one. It seems that many people have successfully built the two cylinder Bobcat version, but I couldn't find a single thing about the Jaguar configuration. Then again, it could be that I just have poor Google-Foo. If you know of a link to one, please post it. I would love to see one.---Brian


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## gus (Jun 22, 2014)

Congrats.You have a runner.  As I said after a hard day of trying to get and obstinate engine to start n run and it just won't budge.
Come back next day and she sprints away off .The fun would be get her to run at sustained idling speed.

We share you pain and joy of engine building. 

OK .Maestro.What's next on the line???


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## doubletop (Jun 22, 2014)

Brian  Thanks for posting the Youtube video. It sounds to be  a great runner but like mine very particular about the throttle control. There is no slamming it open and shut as it will just give up trying to keep up. Min revs I achieved on the Lynx was about 800 and max 5000. I was hoping it would get to 8000 but nowhere near it. That was with electronic ignition that auto advanced to about 30deg BTDC. Of course your advance is static, what do you have it set to?   Pete


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## Brian Rupnow (Jun 22, 2014)

Pete--my ignition is set to about 10 degrees advance. Again, I ask you--do you have vapour shooting out of your carb air inlet like mine does when you watch the video?


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## Brian Rupnow (Jun 22, 2014)

I have one trick left. If it doesn't work, I am out of ideas. I will remove the inlet valve rocker arm and pushrod and put a lighter spring on the valve---let it become in effect an atmospheric valve. If that doesn't work, this may become my first model to go "On the shelf" and be an ornament rather than a running engine.


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## Lawijt (Jun 22, 2014)

Very nice Brian. It is a great runner.
 Can you post a photo from that car behind?? I like too see that.

 Regards

 Barry


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## johnny1320 (Jun 22, 2014)

I if your getting vapor then your intake valve is closing too late or you could have too much valve overlap, also try it with the exhaust pipe removed, exhaust may be too restrictive. Engine looks great Brian!


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## Brian Rupnow (Jun 22, 2014)

Lawijt said:


> Very nice Brian. It is a great runner.
> Can you post a photo from that car behind?? I like too see that.
> 
> Regards
> ...


There you go Barry--My 1931 Ford roadster pickup and I at a car show last year. That was my hobby for 40 years before I got into building small engines.---Brian


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## Brian Rupnow (Jun 22, 2014)

Trust me, my friends, when I say it has been a Hmmmm---Hectic afternoon. I lay down for a nap early this afternoon, but instead of napping, I found I was laying there going over every possible thing I have ever learned or known about small engines. First and most important rule---Assume nothing!!! I found Malcolm Stride's explanation of setting the valve timing very confusing. That could be my problem, not Malcolm's. I came back down to my office and fired up the computer, and arranged the 3D model so that the piston was at 40 degrees before bottom dead center, going in the direction of rotation. This looked nothing like I had initially set things up, so I took the gear cover off and re-timed the gears to agree with what my solid model had shown me. For a while I had removed the pushrod and rocker from the intake valve and put a much lighter spring on, trying to run it as an atmospheric valve. This did work to some extent, but I found that with the lighter spring, the valve didn't close consistently, so I put the strong spring, rocker arm, and pushrod back into the intake side. I want to believe that somewhere, somebody, must successfuly run engines without a head gasket. I have never had that work for me, so I made a very small ring of gasket material that would fit between the cylinder head and the ring around the top of the cylinder body. This increased the come and go compression by a quantum amount. While I had the head off to add the gasket, I remembered some of the problems I had with the Rupnow hit and miss engine caused by too much material in the cylinder head shrouding the tip of the sparkplug, so I set the head up in my mill vice and relieved a bit of the material around the tip of the sparkplug. I noticed that the gas cap on the tank I had "borrowed" from my Webster didn't have a vent hole in it, and I have learned from experience that just loosening the cap doesn't always work, so I drilled a .039" vent hole in the cap. After reassembling everything (except the exhaust system), I gave it a try, and was immediately rewarded by what you see in the video. the engine ran for about 4 minutes, then the damn set screws which lock the big gear to the camshaft came loose, and it quit again. I am beginning to realize that I HATE these small totally enclosed engines. Every time a set screw comes loose, you have to take the entire friggin' engine apart to tighten them back up!!! Next time I will double set screw everything, with two setscrews to lock the gear to the shaft and two more behind them to lock the first set of set screws. At any rate, here is my second sustained run, and if something utterly dreadful hasn't happened to my camshaft, I think I am going to get this thing whipped!!!


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## Brian Rupnow (Jun 22, 2014)

Here is the same video, only this time on Youtube.
[ame]https://www.youtube.com/watch?v=AGzhtfaowk4&feature=youtu.be[/ame]


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## doubletop (Jun 23, 2014)

Brian Rupnow said:


> Pete--my ignition is set to about 10 degrees advance. Again, I ask you--do you have vapour shooting out of your carb air inlet like mine does when you watch the video?



Brian

Apologies: I did get vapour out of the intake but don't now. I had a valve that didn't close fully at the point of firing. As you are getting good compression I'd suggest that you check the valve clearance at the firing point.

But you'd know that?


Pete


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## Brian Rupnow (Jun 23, 2014)

Okay people--I think we are done like dinner. After disassembling the engine one more time, tightening up all the miserable set screws that kept backing off and putting a second set of "locking" set screws behind them, the engine seems to be running quite fine. It is VERY touchy about changing speeds, and is as liable to stall as it is to change to a faster or slower speed, but I think that is just a matter of carburetor setting and ignition timing . I still get the vapor out of the carburetor, but that may just be the nature of this engine. If it is caused by valve timing, it won't go away. If it caused by a bit of leakage at the intake valve, it may go away on its own. This has been a hard won battle, and I think a lot of the problem was created by myself misinterpreting the valve timing instructions.--On any video's of I have seen of the twin cylinder version of this engine, I think I see blowback coming out of the carburetors on them also---of course if they are running the propeller, the airstream hides the blow-back from the carb and you don't see it. This has been a quick/fun/frustrating build, but at the end of it we have another runner to add to my stable of i.c. engines. This makes number seven. I will be publishing a link to the drawing package sometime in the coming week.-----Brian rupnow
[ame]https://www.youtube.com/watch?v=IT00-T0crEI&feature=youtu.be[/ame]


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## Brian Rupnow (Jun 23, 2014)

Thank you guys, for the nice comments. Things generally always get a little crazy for me at the end of a build.This one scared me a little, because until I revisited the cam timing, I was beginning to think perhaps I had built an engine that no-one else has ever built successfully, and that there was some basic flaw in the design that I had missed. I still have not found a video of a running Jaguar engine. I find it very hard to believe that I am the first person to have built and ran and posted about this particular engine. Oh, I have made a LOT of changes, but the bore, stroke, and cams are the same as Malcolm Stride originally planned for. This has been a very fast build, even for me, and it has consumed a very large portion of the past six weeks. It starts very easily now, and runs until I shut off the switch. I find that this engine does not like changes in the throttle setting very much. It likes to run fast---(again, I think the cams are right on the ragged edge of what will work in a single cylinder engine.). In the videos the George Britnell carb clone has the throttle set wide open--and if I slow it down  by closing the throttle it will slow down a very little bit, then stall out. Of course I will continue to tinker a bit with it and see if this can be improved any. I have taken a good look at Malcolm Stride's carburetor plan, and it is very similar to the carb which I have on it. It is a very pretty engine, and terrifically small considering the bore. I thought that I would like to have an engine with a totally enclosed crankcase, but I'm rethinking that now. There is no good, quick way to check the engine oil level, and that oil level is critical to the big end of the connecting rod, which has no bearing on it.---And the big end of the con rod is not accessible to squirt a few drops of oil on like I can with my open crankcase engines. My machining skills continue to improve, as do my trouble-shooting abilities (which are a major necessity when trying to get a new engine started and running.) It's been fun, but I'm glad its over now for a while. I will finish off the drawings and post a download link later this week. Thank you so much to all who followed the thread and those who took time to comment.---Brian Rupnow


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## gus (Jun 23, 2014)

Glad you got it running to your satisfaction. Now the presssure is Gus to finish up and run. I  am still recovering but not much zest and kind of lethargic.


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## Brian Rupnow (Jun 24, 2014)

Here you are guys---I think there are about 60 drawings, all in pdf format. If you discover anything particularly horrible, please let me know.---Brian Rupnow
http://www.mediafire.com/download/7h21s9qko5mhcyk/CANADIAN_CUB_I.C._ENGINE.zip


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## Brian Rupnow (Jun 24, 2014)

Wow--What great fun, to be finished the big thresh and to be able to actually spend some time tuning in the engine and adjusting things to see how much I can improve the performance. The more this engine runs, the better it runs. I am now able to get a much better variance in the RPM range. The engine does get hot very fast----of course, this is a whole different ball game than my hit and miss engines.  I have no desire at the moment to build anything more, but may, in future, think of adding a small belt driven fan that cools the cylinder. I wish I had a variable ignition timing set-up for extra fine tuning, but I'm sure I can live without it.


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## gus (Jun 24, 2014)

Brian Rupnow said:


> Here you are guys---I think there are about 60 drawings, all in pdf format. If you discover anything particularly horrible, please let me know.---Brian Rupnow
> http://www.mediafire.com/download/7h21s9qko5mhcyk/CANADIAN_CUB_I.C._ENGINE.zip




Hi Btrian,

Thanks for the drawings. Will earmark for 2015 build.


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## bmac2 (Jun 25, 2014)

What a ride. That is one nice looking engine Thm:.  Thank you for sharing all the highs and lows of this build. Ive downloaded the plans but it will be a while before Im up to a level where I would feel comfortable starting on it.  Its builds like yours that finally inspired me to start on my Webster.


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## doubletop (Jun 25, 2014)

Brian

Nicely done and a neat variant of the original.

You could always make the water cool jacket. A lot quicker than pulleys and fans.

If you want to try variable advance timing you can do it for $26.

http://www.hobbyking.com/hobbyking/...or_Single_Cylinder_Gas_Engines_14mm_Plug.html 

If you look through the website you may find something better suited to your plug. As you have a flywheel put the sensor on that not the camshaft otherwise you'll get the advance timing wrong with the cam going at half speed.

Pete


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## Brian Rupnow (Jun 25, 2014)

Thanks Pete--I will save that link. The water cooled cylinder is a possibility that I hadn't thought about. BMac--You are right--It is a nice engine, but you want a few simpler ones under your belt before you build this one.---Brian


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## Brian Rupnow (Jun 25, 2014)

This will be the last post about this engine unless I do some fairly major change to it. I will probably make a new piston with proper sized ring grooves in it for cast iron rings and give that one more try at some point. I may try the Philip Duclos method of ring heat treat, which is entirely different from Malcolm Stride's method, and if I do I will post about it. During the video I say something about the "shape of the valves". I miss-spoke there, what I meant to say was a comment about the "shape of the Cams".---Brian


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## Brian Rupnow (Jun 27, 2014)

Well--I did say I wouldn't post anymore on this engine unless I made a major change----I THINK  this is a major change. I needed to put my George Britnell carburetor back onto the twin opposed cylinder engine, so I took Malcolms plans, fiddled them very slightly, added imperial fasteners instead of the metric ones, and redrew them in inches.  This is a $560 carburetor!!! I spent two 8 hour days building it. At my "standard rate" that I have always charged for my design work, plus the "harmonized goods and services" tax which I am bound by law to collect, it would have cost somebody $632.80 for those two days of my labour. Good Lord---If I had to pay for this kind of stuff, I would quickly find a cheaper hobby!!! The engine responds very well to this carburetor. I was fiddling with the needle valve, winding it in more and more with the throttle wide open. The rev's were starting to pick up very good, when suddenly the engine quit and  again has no compression. I took out the sparkplug, and yes, there is still a piston in there going up and down when I turn the flywheel, and the camshaft is still operating. The engine was getting quite hot, so I'm not sure what happened. I have never melted a Viton o-ring, but then again all of my other engines are hit and miss except for the dual opposed cylinder engine, and they all run quite cool. I will do some more diagnostics on the engine tomorrow to see what happened. I understand that the Viton o-ring material can be extremely nasty stuff if melted, so I will exercise rubber glove caution. At any rate, the carb seems to be a success.


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## Brian Rupnow (Jun 27, 2014)

Big sigh of relief---No disaster!! A piece of my headgasket that intruded into the combustion chamber and was left untrimmed had burned to carbon and broke off wedging under the head of the exhaust valve.  I pulled the cylinder off because I knew it would keep me awake all night wondering what was going on with the compression. Two minutes with an exacto knife and a good shot of compressed air to blow everything out and tomorrow I should be back in business. I held the exhaust valve open by pressing on the valve stem and compressing the spring, and a blast of air up the exhaust pipe blew out any remnants that I couldn't see. With this engine, it is a lot easier to pull the cylinder and head off as an assembly than it is to pull off the head by itself.


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## Swifty (Jun 27, 2014)

Very nice engine Brian, I'm glad that you got that problem sorted easily, it runs great.

Paul.


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## Jasonb (Jun 28, 2014)

Thanks Brian, it sgood to know the Nemett carb works OK as I've already made one for my twin.

One reason teh hit and miss engines run cooler apart from the obvious slower speed is that the piston is pumping cold air in and out of the cylinder all the time the exhaust valve is held open which keeps the temp down.

Maybe a small fan belt (o ring) driven off the flywheel a bit like the air cooled Hired Man engines used. Quite simple just a hub and 4 angled blades soldered into a short piece of tube which acts as the pully surface around the outside.

J


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## Brian Rupnow (Jun 28, 2014)

Jason, I agree with you, and I may go in that direction.---Brian


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## Brian Rupnow (Jun 28, 2014)

If it weren't for bad luck, I'd have no luck at all---Doom,Despair, and Agony on me---Wait--Oh No---This isn't Hee Haw is it!!! I reassembled everything this morning, had a couple of good runs, and then the engine quit. A visual examination showed one valve wasn't setting up as high as the other. Hmmmm---That's strange!!! Turning engine over by hand showed exhaust valve, spring and all moving up and down with compression/suction of the piston. Very strange indeed!!! I pulled off the head, and see that my exhaust valve, valve cage and all has come loose from the head and is moving freely up and down in the head. Obviously my guardian angel has an interest in small engines as well and didn't let the whole thing get sucked down onto the top of the piston at speed. This would have been exciting indeed!!! Ever since destroying a valve cage while trying to press it into a cylinder head on one of my earliest engine builds (Kerzel, I think) I have made them a "slip fit" and coated them with Loctite to keep them in place. The flange keeps them from flying out of the cylinder head under pressure. I NEVER imagined one of them being sucked INTO the cylinder.  I don't think its a really big deal. I will take my "automatic punch" and put a number of punch pricks around the inside of the hole in the cylinder head to upset the metal a bit, then clean everything with laquer thinners, re-Loctite things, and press the cage and valve back into place.


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## doubletop (Jun 28, 2014)

Brian

Encouraging to hear you had good results with the Nemet carb. My Bobcat build was my first ever I/C engine so I had no yardstick to measure the results. (yes truly a beginner in my case)

As for the valve problem Interesting? But all good info for the other builders. I had thought the valve spring sitting on the shoulder on the head would act to pull the valve and the valve pull the seat into the head. If its come loose  either the valve too tight in the guide or more likely the loctite can't stand the heat? In one of the videos of a Nemet engine the exhaust is glowing red hot. (I can't find it at the moment). Then again maybe the Nemet carb is running lean and another source of overheating?

The thought of melted vitton rings? Isn't overheating Vitton a safety problem?

Pete


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## Brian Rupnow (Jun 28, 2014)

It might be a bit tricky getting the positioning right, but a #6-32 pan head screw positioned so as to catch the edge of the valve cages but clear the head of the valves would be an easy "safety" add on. It would only require a #6-32 hole be tapped into the aluminum head. I would tap it all the way through and put a safety nut on the outside of the head to keep the screw from unthreading itself. There is sufficient head to piston clearance to clear the head of the screw with no difficulty.


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## Brian Rupnow (Jun 28, 2014)

doubletop said:


> Brian
> 
> Encouraging to hear you had good results with the Nemet carb. My Bobcat build was my first ever I/C engine so I had no yardstick to measure the results. (yes truly a beginner in my case)
> 
> ...


The spring doesn't set on a shoulder in the head. The spring sets on top of the valve cage. If the valve gets a bit sticky in the cage and the Loctite bond between the cage and the head isn't good, the rocker will push the valve and the cage down into the cylinder.


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## Jasonb (Jun 29, 2014)

Brian what Loctite did you use as some have a higher temop range than others, Although mu cages were a nice press fit I also added a drop of 648 for good measure.

Pete, its the Lynx with the red hot exhaust not a bobcat though still pressed in.

[ame]http://www.youtube.com/watch?v=wTq0ogyTFEc[/ame]


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## Swifty (Jun 29, 2014)

Wow, I hope that the exhaust on my Lynx doesn't get that hot. I see that the exhaust is made of that thin wall flexible pipe, probably more prone to getting red hot.

Paul.


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## Brian Rupnow (Jun 29, 2014)

I have (hopefully) solved my valve cage issues and reassembled everything, with the Nemett style carburetor. A minimum of messing about this morning had it running as you see in the video. I'm quite happy with it, but it really must have a fan.--It gets far hotter than I am comfortable with. I want to keep playing with the timing and the carb until it ticks over at a much slower idle and runs consistently, but I think I am 99% there. I have been saving a small electric motor with a plastic bladed cooling fan on one end of the armature, and it may be exactly what I need for this.
[ame]https://www.youtube.com/watch?v=xr3Hzut5Gj0&feature=youtu.be[/ame]


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## Brian Rupnow (Jun 29, 2014)

Oh Bummer!!! The fan I've been saving is too much hub and not enough blade. It's a bit too large as well. The ideal size would be 2 3/4" o.d. with a "smallish" center hub suitable for a 3/16" or 1/4" shaft. I could probably cut down the diameter of this fan to what I need, but then it would be all hub and very little blade. I have a very strong aversion to having my fingers whacked by a metal fan or propeller, so will enclose whatever fan I use with a band of aluminum incorporated into the mount and bearing. I guess I will have to go and patrol the dollar store or??? to see what I can come up with.


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## Brian Rupnow (Jun 29, 2014)

Hah---Look at that cute little devil!! $8 at the computer store--the diameter is exactly what I wanted and the pitch is right to blow cool air onto the cylinder. I would have preferred some color other than white, but you work with what you can get (there is always plastic paint). I have never had one of these things apart before to know how to put a hub/shaft set up on it, but I'll know in about 10 minutes---


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## Brian Rupnow (Jun 29, 2014)

After thoroughly trashing the guts out of it, I find that there is a nice concentric ring cast into the plastic in the center. The plastic fan itself has a thin metal ring which is pressed into place over some "snap-lock" thingies that are cast into the inner diameter of the plastic fan itself. Since this fan will not be turning at warp speed, I'm not horribly concerned about balance, so a round piece of aluminum or brass or even possibly steel with a hole for the shaft in the center can be Loctited to the inside of that thin steel ring. I have to do some thinking on this, and since I have an abundance of 10mm ball bearings I may incorporate one into the hub. If I do this right and put an o-ring groove in the outside of an extended hub with the bearing in it, then I don't need a live shaft at all.


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## gus (Jun 29, 2014)

*Carbs,*

I have one OS Carb bought for the Rupnow H&M Engine which did  perform well and about to buy another OS Carb good for Nemett-Lynx Engine. Also plan to make the Nemett-Lynx Carb too. It is a hard fact that carbs must match to give good throttling range.

Been watching Nemett-Lynx Engine Videos. Meanwhile the finishing line is a mile away for Gus. I have to cook up some tooling to cut the cams. Will be tapping Brian's and Paul's brains for expertise.Taking my sweet time to finish up.

Good News. The valve guides were a bit tight press-fitted in. Made and throw away 4 pieces as the fit was either sloppy or only tight push fit. Will cut new valves and lap today. The valve springs using the prescribed SWG 20 seems a bit too strong. Will try out softer
springs.


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## doubletop (Jun 30, 2014)

Jasonb said:


> Pete, its the Lynx with the red hot exhaust not a bobcat though still pressed in.



I had thought it was but it still indicates the sort of temp the exhaust of these things get too. 300deg C won't cause a red hot exhaust but it will undo locktite.

I had to go back to the drawing to prove myself wrong. On my lynx I didn't like the valves seating on the ally so did a hybrid

















You'll see the springs sit on the original ally shoulder. However the bobcat/jaguar valve guide/ seats don't have that shoulder in the head







Pete


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## Swifty (Jun 30, 2014)

The video of the Lynx with the hot exhaust appears to have a water cooled jacket and flywheel. If it had a propellor it would be cooled by the back draught.

Pete, I went and looked again at your video of the engine running, the propeller seems to be a good size for the engine, what size is it? I will only be using a prop for display on my bookshelf, so will start looking for a cheap one.

Paul.


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## Brian Rupnow (Jun 30, 2014)

It wasn't a big deal to suss out a design for my fan, and no big deal to build it. The only thing I don't really like is that the fan ends up being almost as big as the engine.


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## gus (Jun 30, 2014)

doubletop said:


> I had thought it was but it still indicates the sort of temp the exhaust of these things get too. 300deg C won't cause a red hot exhaust but it will undo locktite.
> 
> I had to go back to the drawing to prove myself wrong. On my lynx I didn't like the valves seating on the ally so did a hybrid
> 
> ...



I sort of trust Malcom's valve seat design and now I have some doubts. May have to put in valve inserts too. Please post same drawing. However will spin/run engine before put in the valve seat inserts.


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## doubletop (Jul 1, 2014)

Paul

The prop is a Master Airscrew S2 Series 16x6 part # MA1660S from HobbyKing

Gus

No drawings I just winged it with some notepad sketches. The Bobcat came after the Lynx so I guessed Malcolm had realised that bronze seats were needed. Get the Bobcat drawing to see what is required and make the internal sizes to the Lynx dimensions and the the external dimension about 1.5mm larger. There is plenty of meat on the Lynx head to accommodate these. Insert the cam seats before you drill the ports in them. You'll notice that I've also put bronze sleeves in for the cam followers. 

Brian

Apologies fro hi-jacking your thread

Pete


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## doubletop (Jul 1, 2014)

Brian Rupnow said:


> It wasn't a big deal to suss out a design for my fan, and no big deal to build it. The only thing I don't really like is that the fan ends up being almost as big as the engine.



Brian

It occurs to me you could have made the water cooled jacket by now, and people would still be able to see the engine 

I did see somewhere a magnetically coupled water pump, no need to worry about sealing the drive shaft. I just couple my water jacket up to the water tap and trickle water through the jacket.

Pete


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## doubletop (Jul 1, 2014)

Just found this

http://www.hobbyking.com/hobbyking/store/__11601__Water_Pump_for_Gas_Engine_Boats.html?strSearch=water%20pump

Hide it in a brass tank?

Pete


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## Brian Rupnow (Jul 1, 2014)

I'm not sure just what to do. The engine is running good as it is. Any fans I have designed look so big and clunky that they overwhelm what is really a pretty little engine. As long as I don't run the engine for more than 10 minutes at a time, I probably don't have to do anything. What do the Bobcat and Lynx guys do with their air cooled engines without propellors? How long do they run at one time.---Brian


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## GailInNM (Jul 1, 2014)

Brian,
In the "For What it Worth" department: When I built my first "Tiny" using a Viton piston ring it ran very hot. After changing to a lapped cast iron piston in a CI cylinder the temperature dropped considerably. I made temperature measurements at the time, but did not record them but as I recall it was about 50 degrees F.  This was running about 6000 RPM.  I converted to hit and miss shortly afterwards so did not do any further checking.

I don't know, but you might see similar results if you go to the cast iron rings as you have indicated that you might do in the future.
Gail in NM


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## Brian Rupnow (Jul 1, 2014)

For what it's worth--I learned two things today. Firstly, the Jaguar carburetor will work well with the throttle spool vertically aligned, as you see it in the last video I posted.  But--The caveat is that when its set up like that, the needle valve ends up on the bottom of the carb, and is consequently lower than the gas tank--and it will slowly drip-drip-drip around the needle valve threads until the gas tank is empty after you have shut down and walked away from the engine. Second thing I learned, is that when you turn it so the throttle spool is horizontally aligned, (the way Malcolm intended it, I believe), and the exhaust system is set up like mine, you can burn the Hell out of your thumb when trying to blip the throttle handle!!!.----Tomorrow I will build a longer throttle handle. As far as a cooling fan goes, I am still undecided. Since it is Canada day here, all of the stores are closed, so I haven't been able to do any searching for a 2" diameter fan blade with a small hub.


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## Brian Rupnow (Jul 2, 2014)

After much searching, I found a fan at Acklands-Grainger, aluminum, 10 blades, 2" diameter, small hub bored for 3/16" shaft. Its about 21 down from the top of the attached link. The store in Barrie was able to bring it in for me, but its going to take about a week. That's fine by me---I don't feel like any more machining right now anyways, at least for a while. The engine is running excellently, and I'm not going to mess with it for a week. I did download 9 pages of information on making piston rings that Steamer had posted as a pdf file. The cylinder now has such a high polish inside from running the Viton ring that I may just build a water cooled cylinder and a new piston, and play with that until I can make a set of rings that will really seal.
http://www.grainger.com/category/fan-blades-and-propellers/hvac-and-refrigeration/ecatalog/N-jr8Zh9e


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## hedgehog (Jul 2, 2014)

well whats next?  when the weather turns this fall you will have to build something    Please say V8 , id love to see your skill and artistic slant on one.


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## Brian Rupnow (Jul 2, 2014)

Hedgehog--Next will be to get the fan mount and housing fabricated and installed, then try my luck again at the cast iron rings. A V8 is not in my future. I do all of my machining manually, no CNC. As a consequence, there is simply too much machining for my taste in an 8 cylinder engine. I would rather stick with new and different (to me anyways) one and two cylinder engines.----Brian


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## Brian Rupnow (Jul 3, 2014)

I've been playing around this morning, designing a shroud for the 2" diameter fan made from a short piece of automotive exhaust tubing, some 1/2" diameter hubs, and some 1/16" diameter spokes to hold the hub in place. Hubs will have brz. or brass bushings with 3/16" bore. At this size I can actually set it in line with the flywheel and just come in underneath the exhaust header. I haven't shown the pulley and shaft yet, but would pick up the o-ring drive from the drive hub, not the flywheel. This is a lot more aesthetically pleasing to me than the previous fan design. Still haven't shown mounts yet, but I can't really do anything until I have the fan blade here.


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## gus (Jul 3, 2014)

Very good looking fan and shroud. Brian has 1001 design ideas. Quick & fast on the draw.th_wav

Now looking at mini computer fan if engine heats up to fast. May put in water-cooled jacket and radiator. 

 Foot Pedal Speed Controller for fishing line spooler done and been on my mind for months and now R.I.P. to allow Gus to move on to Cam Cutting with peace of mind. Some prepping work required to get good cams.


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## Brian Rupnow (Jul 4, 2014)

Hi Gus--good to hear from you. A mini computer fan will work, but they have an enormous hub in relationship to the length of fan blade. This is not problem if you want to leave them electrically powered, but if you drive them with an o-ring drive off the engine that big hub isn't moving any air. That is why I searched for a small diameter fan with a small diameter hub. If I were to start this project over again, I would go water cooled. You however, have already made your air cooled cylinder---in fact I don't think the Lynx plans even have a water cooled option, do they?---Brian


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## Brian Rupnow (Jul 4, 2014)

Okay--I think I have the final draft--(pun intended). I decided that the 1/16" diameter spokes might be a bit difficult to fab properly, and the way I had things the fan would have to be trapped inside the cage as it was welded up. This is never a good idea. This morning I was working on supports, and decided to go with one support off a head bolt and one support off a cylinder bolt. As I was doing this, I decided to remove the spoke and hub assembly from one side of the tubular guard and cantilever everything off the side facing out away from the cylinder. This let me replace the round spokes with 3 pieces of 1/16" steel plate and the fan is no longer "trapped" as it can be installed from the open side of the guard which faces the cylinder before it gets bolted in place. There will be a 3/16" bore bronze bushing in the hub. The pinkish colored pulley (5/8" outer diameter) and 3/16" shaft will be silver soldered together. The fan hub is attached to the shaft with set screws. The 1.5" diameter drive hub attached to the face of the flywheel will act as the driver for the o-ring drive belt. Thus the fan will rotate at a bit more than twice the speed of the engine.


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## doubletop (Jul 4, 2014)

Brian Rupnow said:


> I don't think the Lynx plans even have a water cooled option, do they?---Brian



Both have a water cooled option, I did the Bobcat water cooled and glad I did with the problems you are having. The second cylinder wouldn't get as much cool air as the front one.

I did the Lynx air cooled.

Pete


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## doubletop (Jul 4, 2014)

Brian

Find a copy of the John Bogstandard instructions on hand machining flywheels. You could make that outer casing from one piece of aluminium. I'll see if I had a link to in in my French Beam engine write up

http://madmodder.net/index.php/topi...PHPSESSID=pmr4olh1c90iclecgvtpfmhmf3#msg55366

Pete


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## Brian Rupnow (Jul 5, 2014)

Doubletop--I know I could make it from one piece, but I like fabricating with mild steel as well. What I have shown poses no real problems. Remember--in my previous 40 years of building hotrods I probably sewed together 300 old car bodies, where I had to create more metal parts with hammer and torch than the cars had on them.----Brian


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## doubletop (Jul 5, 2014)

Brian

I was  more thinking along the lines of making it out of a material in keeping with the rest of the engine.

Pete


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## Brian Rupnow (Jul 11, 2014)

This morning was show down time. I had finished the shroud and brackets for the fan yesterday afternoon, and painted the shroud. This morning I got up and added some set-screws to the fan hub, and made up a shaft and pulley for the fan. I was very fortunate in finding a rubber o-ring of the correct length, and the fan was installed on the engine. I am very pleased with the results, and the 2" diameter six bladed fan which is travelling approximately at twice the engine speed puts out a very noticeable breeze over the cylinder cooling fins. The engine exhaust is a bit smoky, because I was running some two cycle oil with the naptha fuel to provide lubrication for the Viton piston ring.--The oil to fuel ratio is 1:20, but I think I can safely cut that back to about 1:35 for future runs. The engine has a wet sump and splash lubrication of the con rod big end.
[ame]https://www.youtube.com/watch?v=XVPX5MXDXrQ[/ame]


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## johnmcc69 (Jul 11, 2014)

Nice job Brian! The fan looks great.

John


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## Tanshanomi (Jul 11, 2014)

As I said in another thread, I bought my new SB 8K to make parts for my vintage motorcycle project, and just happened to stumble on HMEM while Googling information about my lathe. I had never considered ever making a model engine, but I read this thread from front to back and it has really inspired me to start thinking in that direction. Your detailed and clear record of the build process is very useful and appreciated, and what a great little engine you ended up with! Glad to see you've gotten it into "fan"-tastic shape (sorry, couldn't resist the pun). Thanks for all the effort documenting this.


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## doubletop (Jul 11, 2014)

Brian

That's looking really good and those viton piston rings seem to do the job. From my experience and the videos I've seen of others plenty of oil gets past the CI rings. The handle of your ignition box would then be covered in oil.

If I ever get round to the flat 4 version I have in mind, then Viton rings will be the way to go. There are no drawings for a flat 4 but if you look at the drawing for the bobcat in-line twin there is plenty of room on each of the journals for another conrod. Make the journals at 180deg and not inline and you have a flat four twin cam.

Pete


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## bmac2 (Jul 12, 2014)

Great looking and running engine. Glad to see youve solved the cooling problem. So any thoughts of making it do some work?


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## Jasonb (Jul 12, 2014)

Pete you can get a more compact engine with a central single cam, just put two of these end to end.


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## Brian Rupnow (Jul 12, 2014)

No work yet for the Canadian Cub. I still want to make a new piston with cast iron rings. Jason--very sharp looking engine.---Brian


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## BronxFigs (Jul 12, 2014)

You guys amaze me every time.


Frank


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## doubletop (Jul 12, 2014)

Jasonb said:


> Pete you can get a more compact engine with a central single cam, just put two of these end to end.



Jason

I had wondered how you were going with your twin but I thought you were going to do a V? Flat makes the ignition timing easier. I'll guess you have a thread somewhere that I haven't found. 

I had considered a single cam but I haven't seriously looked into any design other than looking at the existing drawings. For the single cam I assume you have some long followers and some way of supporting them?

Is there a link?

Pete


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## Brian Rupnow (Jul 12, 2014)

Let's go back in time to where I first made cast iron piston rings. I ran them in for two hours, installed on the piston, and couldn't seem to get any compression. I was in a hurry to get the engine running, and needed to prove to myself that the no compression issue wasn't something other than the rings. I modified the piston to accept Viton o-rings, and moved on to a point where the engine was running. I have gradually improved the engine, until now it runs well and has so much compression I can barely turn it over by hand. Yesterday I pulled those two original rings out of their storage container, and had a good look at them with a magnifying glass. One ring had 3/4 of the surface worn from full contact with the cylinder wall, and one quarter which was still black from the heat treating process, so obviously not sealing at all in that area. The other ring however, had a nice even wear pattern all the way around the ring, with no black showing at all. To me, that says that it should have given me compression at the time. This morning I made a new aluminum piston, with the correct depth and width of ring grooves to suit the batch of 12 rings I originally made, and fitted the one good heat treated ring onto the piston. I have two heat treated rings left from the first batch of "good" heat treated rings, and I will install one of them  in the other ring groove tomorrow. If I can find a piece of cast iron long enough in all my cut-offs tomorrow, I may make up a dummy cylinder and use the same 7/8" reamer as I used when I made my original cylinder. That should give me something to "play with" until I can judge if these rings are going to seal at all. If they do, its a very simple matter to pull the cylinder off the engine and swap pistons.


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## Cogsy (Jul 12, 2014)

I'm sure you'll have success Brian. So far I've managed to make 2 good sets of C.I. rings from 2 attempts, and you skills are far ahead of mine.

I've never tried running the engine in prior to attempting to start it and never lapped the bore either as my experience in full sized engines makes me wary of glazed or polished bores. On initial install both of my engines were way down on compression, although they did have a bit. Once the other issues were sorted out and the engine began to fire, the compression increased very quickly. Still being fairly inexperienced at this, I don't know if I have optimum compression compared to an oring, but I certainly get enough for the engines to run consistently.

Good luck and I'll be watching with interest.


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## ratto93 (Jul 13, 2014)

Hi, I'm begginer in machining, but your works look very good. 
Sorry for my not good english, have a nice day.
Regards, Alessandro


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## Brian Rupnow (Jul 13, 2014)

This mornings ring experiment was another FAIL!! I made up a dummy cylinder from cast iron, same bore, stroke, and interior finish as the cylinder on the engine. I tried my new piston and cast iron rings in the dummy cylinder, and it had SOME compression, but nothing compared to what you would get from a viton o-ring. A bit of light oil made it a bit better but not much. I decided to try it in the engine, so pulled the old piston and Viton ring out and put the new piston with cast iron rings in. Initially, it did have some very weak compression, and at high drill speeds I could get the engine to fire and run along with the drill, but not on its own. I tried about a hundred different needle valve settings, but nope, no way the engine was going to take off and run on its own. I even tried straight automotive gasoline with no oil added and that didn't improve things in any way. Eventually, even the initial weak compression I had felt faded away to nothing. I'm not sure what to do next.---Maybe take up needlepoint!!!


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## Brian Rupnow (Jul 13, 2014)

An update. I couldn't get any compression with my first attempt today with cast iron rings. I pulled the cylinder off, which by now had a mirror like polish on it from running with the Viton ring, and honed it with my 3 stone brake cylinder hone, enough to "unpolish" it, then reassembled the engine again with the cast iron rings. This time I did have compression. Not very much, mind you, but enough that the engine would fire.---and thats all it would do. I musta screwed around for 3 hours trying to get it to run, and as the day wore on, I got progressively longer periods of running. This, I assume, was a result of the new cast iron rings very gradually "seating" in the cylinder. After 3 hours I said "enough is enough" and decided to try something else. I pulled out the sparkplug, made up a very small aluminum pulley for my big old bale elevator motor, and hooked things up with an o-ring drive. I gave a few squirts of oil down the sparkplug hole, topped off the crankcase oil, and plugged in the electric motor. It's setting on my test bench out in my main garage, wailing away at about 1800 RPM. I'm going to let it run like that for 3 hours and then give it one more try. If it has by then developed enough compression to run with the cast iron rings, I will be a happy camper. If it hasn't, I will put the piston with the Viton ring back in it and leave it alone. It does run good with the Viton ring, and the fan does keep it cool enough to run for extended periods of time.


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## bmac2 (Jul 13, 2014)

Fingers and toes crossed. Youve got a good running engine already but the cast rings would be another feather in your cap.Thm:


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## doubletop (Jul 14, 2014)

Brian

Neat idea. I had a frustrating experience trying to get both of mine to start. I had no idea what to expect, so tweaked carb, ignition, valves, rings until it eventually started. Somebody had asked how much compression i had and I eventually worked on that.

There's a message here for all the other builders, get the compression sorted before you try to start it otherwise you'll be wasting your time. Expecting the rings and valves to seal and bed in enough to get the thing to start just doesn't work.

Pete


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## Brian Rupnow (Jul 14, 2014)

Doubletop--I have read accounts of many other model engine builders who don't even try to start their engines until they have ran them in this way for 8 to 12 hours.---Brian


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## Brian Rupnow (Jul 14, 2014)

After 4 hours or "running in" to get the rings to seat, a couple of very minor tweaks to the timing, and some straight hi-test automobile gas, we are up and running with cast iron rings!!! This is a first for me, and I am thrilled!!! At first the engine would run with the cast iron rings, but didn't develop enough power to turn the fan. I kept tweaking the needle jet and the ignition timing (which are really the only two things that there are to tweak) until finally the engine began to run more powerfully and began to get hot. I put the belt back on the fan and finally the engine was able to run with the fan and keep running. I am now getting good sustained runs, and as the rings wear in and seat more, the engine seems to be running better and better.



[ame]https://www.youtube.com/watch?v=3iqqoDeG6vM&feature=youtu.be[/ame]


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## bmac2 (Jul 14, 2014)

Congratulations!
And another feather in your cap.
Ive read a couple of posts that say how with cast rings they can take some time to run in. 
Great build.


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## Brian Rupnow (Jul 14, 2014)

-I thought about running the rings in dry. I was afraid to in case I scored the cast iron cylinder wall. My thoughts were that running the rings in with oil in the cylinder (sparkplug removed of course) would do the same thing, just take a lot longer. Now that I have the engine running, I am using straight unmixed gas in the engine. The lubrication is splash oiling from the sump. Running with straight gasoline will get rid of a lot of the oil film in the cylinder, and the rings should seat more in a relatively oil free environment. That little fan sucks up a lot of the engines power, preventing it from getting into a higher rev range than what you see in the last video posted. Right now the ratio between pulleys is 2:1 so the fan is being driven at twice the engine speed. The engine is running cool as a cucumber so I am going to try a 1" pulley on the fan, changing the ratio to 1.5:1, so the fan will run about 1 1/2 times faster than the engine and take some of the load off it to allow it to rev a bit higher.


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## gus (Jul 14, 2014)

Been using rings bought from USA vendor for the Webster and Rupnow Engines. True ,they have to be run in and seated/sealed well. Indication would be non-sustained run but after a few more spinning sessions,the spinning gets sustained.Pehaps this was why the H&M with Rupnow engine did not come on well till piston rings seated in.
Now waiting for engraving cutter to arrive from UK to engrave the RT graduations and from there
cam cutting can begin.RT table lapped and worm wheel and worm meshed well though a bit tight but crankable and eventually will slacken a wee bitty.
Now dreaming about my own Nemett-Jaguar running next year. After Lynx would doing upgrading/repairs on the machine tools. About time to replace spindle bearings of the 14 year old US$100 Bench Drill Press which is now part of Gus.


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## Brian Rupnow (Jul 14, 2014)

Hi Gus. This has not been an easy engine to build. No, let me correct myself. The engine was as easy to build as any comparable closed crankcase four cycle engine would have been, I suppose. The difficult thing for me has been getting it to run the way I like my engines to run. I prefer my engines to operate somewhat slowly, not unlike steam engines. This engine is cammed to rev higher than I am accustomed to, and it really doesn't like to idle at "tick-over" speed. My dual opposed piston engine will idle very slowly, but I had to resort to quite a large diameter flywheel to make that possible. This engine has only a 3" diameter flywheel, and although it might idle well in a twin cylinder configuration where there is a power pulse on every 360 degrees of rotation, as Malcolm Stride originally designed it, there are some issues with the idling RPM in it's single cylinder configuration, where you only get one power pulse on every second 360 degree rotation. I have learned a lot from building this engine, and as my video's show, it does run. I think if someone really wants to build this engine, that they should build it as a twin cylinder.


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## Cogsy (Jul 14, 2014)

Congrats Brian. As I said, I never had any doubt you'd get C.I. rings mastered. I would be interested to know, once it's completely run in, how compression compares between the Viton and C.I. rings.


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## Swifty (Jul 15, 2014)

Good going Brian, persistence gets you there in the end.

Paul.


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## doubletop (Jul 15, 2014)

Brian

I've certainly learned something from your experience as you've precisely described mine, with both engines. So much so I now have "make new piston with viton rings" on my todo list if only to try it out and confirm for myself that compression is the problem with poor running. Not carb or ignition.

Thanks again

Pete


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## Brian Rupnow (Jul 15, 2014)

Alright!!!--This thread is officially finished. the engine runs, it runs reasonably well, and it runs with cast iron rings. The fan does keep the cylinder and head cool, after running 3 tanks of gas thru back to back at 20 minutes per tank. I never did solve the blow back thru the carburetor issue, and I think that is purely a factor of too much valve overlap at top dead center for this engine in a single cylinder configuration. I have found that yes, the Loctite does hold the cams to the cam shaft without slipping or coming unstuck, which is a really good thing to know. this is the first engine I have built which uses a jockey gear between the crankshaft gear and the camshaft gear, and that works fine. The ability to determine whether there is enough crankcase oil in the sump to keep the big end of the con rod lubricated by splash lubrication is a very "iffy" sort of thing. You have no access to it to put a drop of oil on it, and there really is no good way to check the oil level, that I have found. If you don't run water cooled cylinders nor a propeller, you will definitely have to fabricate some type of belt driven fan as I did, or this engine will run way too hot. I don't think I will try any more engines with cast iron rings. There is far too much screwing around involved, and even after 6 hours of continuous running, the engine had nowhere's near the compression it did with a Viton o-ring. It is a very pretty little engine, and I have used up May, June, and a damn good chunk of July to get to this point. Thank you so much to all of you who have followed this thread, I know it has gotten very long winded.----Brian


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## Brian Rupnow (Mar 3, 2015)

During my engine selection to find an engine that would suitably run the buzz saw under a full load, I tried a number of different engines out of my "stable". I couldn't get this engine to start, so I set it aside. Yesterday, I got it back up on my test bench, and tried every trick I know to make it run. Heck, I couldn't even get it to fire. And yet, it had a ferocious spark when the plug was laying out on the cylinder head, the spark seemed to be occurring at the right time, and the engine had lots of compression and new fuel. After trying everything in my "bag of tricks to get engines running"---which is considerable, I decided that I would have to tear it completely down and do a part by part inspection of what was going on. This morning I thought, "Well, there is only one thing left to try before I tear everything down."---(which I really didn't want to do!)  I changed out the sparkplug for a spare plug that I have been saving. The engine started immediately and ran like a trooper!!! I have never seen a miniature sparkplug go bad like that before---fires like crazy under no compression load, but doesn't fire under compression. I have heard about it, and probably at some time in my hot-rodding past have even experienced it and forgotten about it.--At any rate, I am certainly glad I didn't have to tear the engine apart.---Brian


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## Brian Rupnow (Mar 3, 2015)

The engine still occasionally coughs back through the carburetor when running at full throttle, and I still see a bit of mist coming out of the carburetor intake, which should never happen. As much as I like the look of the swoopy exhaust pipe turning 180 degrees and discharging back towards the opposite side of the engine, I wonder if that creates enough back pressure at higher RPM to interfere with the smooth flow of gasses during the exhaust stroke. The exhaust valve and intake valve are both open at the same time for a short duration at the end of the exhaust stroke, the theory being that the already flowing exhaust gas will actually pull the incoming gas (vapour) and get it moving in the intake system to overcome the inertia which tends to make the intake vapour column remain at rest (as in not flow) until the piston has already began it's descent in the cylinder during the intake stroke. There may just be enough resistance to free flow in that 180 degree bend that it is preventing this "scavenging effect" from happening. I might just have to fab up a straight pipe to see what effect that has.


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## canadianhorsepower (Mar 3, 2015)

Brian Rupnow said:


> The engine still occasionally coughs back through the carburetor when running at full throttle,


 
Hi Brian
I'm under the impression your engine is trying to burn already burn gas 
that's been thrown in the air like running an EGR valve at idle
  make it longer it will change the charge time speed and increace the engine torque band

cheers

Luc


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## Jasonb (Mar 4, 2015)

Might be worth a try on my twin I don't see anything like the amount of blowback that you had on the videos and I've only got short exhaust pipes but being an opposed twin the intake pipes between central card and heads is a lot longer so may "soak up" any blowback


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## Brian Rupnow (Mar 4, 2015)

I replaced the exhaust pipe with the nifty 180 degree bend this morning, with one which is basically a straight pipe. This was supposed to cure the problem with vapour coming out of the carburetor intake. It didn't!!!
[ame]https://www.youtube.com/watch?v=8Rb9rNZgkrc&feature=youtu.be[/ame]


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## canadianhorsepower (Mar 4, 2015)

Brian Rupnow said:


> I replaced the exhaust pipe with the nifty 180 degree bend this morning, with one which is basically a straight pipe. This was supposed to cure the problem with vapour coming out of the carburetor intake. It didn't!!!
> https://www.youtube.com/watch?v=8Rb9rNZgkrc&feature=youtu.be


 
Hi Brian
I would put the exaust 180 up like zommies on a dragster.
the fact the the more RPM the more is does it makes me think
that your valve are floating  (need a stronger spring):hDe:
or your points are floating, then again a spring bending should cure this. :hDe:

cheers
Luc


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## swnf (Mar 4, 2015)

Long time lurker but it may be reversion


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## Brian Rupnow (Mar 4, 2015)

And what, pray tell, is reversion?


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## swnf (Mar 4, 2015)

Unwanted reversal in the normal direction of the gas flow.
"Intake reversion because of late closing of intake valve"
This is from the book Reher-Morrison
Championship engine assembly 

I think this forum is the best 
Just trying to learn all I can from you guys. Not trying to offend just a guess


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## Brian Rupnow (Mar 4, 2015)

Swnf--No offence taken. I suppose that could be the problem. Very hard to analyze that one.---Brian


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## Jasonb (Mar 5, 2015)

Brian, do you have your points on the crankshaft or cam shaft? If on the crank and you are using lost spark then maybe on the odd occasion the lost one is igniting the mixture?

Does it do it if you adjust advance & retard the spark?

I've not seen it on mine and that has the same cam profile and timing give or take a bit for how we have set the timing gear.

http://youtu.be/9L64ItB3xgw


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## Brian Rupnow (Mar 5, 2015)

Jason--EDIT--I had to take a closer look. The points are operating off the cam shaft, so I am not getting a "wasted spark".---Brian


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## Brian Rupnow (Mar 5, 2015)

swnf-The exhaust cam and the intake cam are fixed in position relative to each other by being Loctited to the camshaft. I can not change much in relationship to the intake cam because anything affecting the intake cam also affects the exhaust cam. The cam timing on this engine is given by the original designer, and there is a definite overlap of valves both being open at the same time as the piston approaches top dead center on the exhaust stroke. When an intake valve first begins to open, there is very little flow through it because inertia tends to keep the column of air in the carburetor intake "at rest" until the piston begins it's descent on the intake stroke. That is why the intake valve actually begins to open before the piston reaches top dead center on the exhaust stroke. As well, in order to fully remove the exhaust from the cylinder, the exhaust valve stays open for a few degrees after top dead center. The theory is that the column of exhaust in the exhaust pipe is already in motion, and inertia will keep it flowing until the valve closes, and this flow will actually help to start pull a fresh charge of unburned fuel through the intake valve which is beginning to open at the same time.. The same effect takes place when the piston approaches bottom dead center on the exhaust stroke. Most of the power has been extracted from the burning charge of fuel by the time the piston has traveled roughly 2/3 of the way down the bore, so the exhaust valve actually begins to open before bottom dead center on the power stroke so that any expansion left in the still burning charge of fuel will start the gasses flowing out the exhaust system. The intake valve, which began to open before top dead center on the intake stroke of the piston stays open all the way through the intake stroke, and stays open after the piston passes bottom dead center on the intake stroke and begins to ascend on the compression stroke.


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## Cogsy (Mar 5, 2015)

Based on what you explain Brian, and on some small commercial stationary engines I have experience with that actually hold the intake valve slightly open at very low rpm (supposedly makes it easier to pull-start as it reduces compression), it seems to me that your valve timing is slightly out.

If this was the case then your exhaust valve would be closing slightly before TDC, meanwhile your intake valve would be open for slightly longer before TDC than designed (this probably wouldn't matter if the exhaust valve was still open). Then the residue exhaust gases would have nowhere to go for the last bit of upward piston travel except out the intake. 

I don't know if it's possible with this design to minutely adjust the valve timing (I know it must be close now as it runs so well) but if it is that's what I'd try. I imagine there is a little more hp in the engine once you fix this issue as an added bonus.


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## Brian Rupnow (Mar 5, 2015)

Cogsy--Nice to hear from you. I guess that will probably be the next thing I do, is try to adjust the valve timing. Since the largest gear is held to the camshaft with dual set screws, it is possible to make very fine adjustments. It's just that the way this engine is built, it requires a major disassembly of the engine to get at the adjustment. I'm just killing time these days, farting around with small engines and hoping for the weather to warm up so I can get outside a bit and do other things. We have just had the coldest February ever recorded in this part of Canada, and so far March hasn't been any better. I don't feel like building anything, and I'm starting to get "cabin fever" from being in the house so much all winter.---brian


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## Charles Lamont (Mar 5, 2015)

Any chance the inlet valve is occasionally failing to close properly?


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## Brian Rupnow (Mar 5, 2015)

Charles Lamont said:


> Any chance the inlet valve is occasionally failing to close properly?


No Charles, I have quite beefy little springs on both valves, and the valves slide very smoothly in their guides. I run a small percentage of 2 cycle oil with my fuel to keep the Viton o-ring on the piston lubricated, and consequently all of the top end is very well lubricated inside, and I apply lube oil manually to the exposed rocker arms and any external pivot points.


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## Jasonb (Mar 5, 2015)

One thing that would be easy to try without a strip down is to slacken off the adjusting screw on the inlet rocker a fraction, this would mean the cam would have to take up the gap before it starts to open the valve so it would open a bit later. Hopefully the fact it closes a bit earlier won't affect things too much.


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## petertha (Mar 5, 2015)

Brian, is there a chance either the locktited cams or set-screwed gear train gave shifted slightly? Is there a way to validate valve Int/Exh open/close timing relative to TDC with a protractor wheel or whatever like you had it originally set up?


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## swnf (Mar 5, 2015)

Could it be the intake valve bouncing or "float"


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## Brian Rupnow (Mar 5, 2015)

Float would be caused by excessively high rpm or too weak of valve springs. It's not that. The gears have double set screws with "back-up" set screws behind them to prevent loosening off. I still have the degree wheel I used for my original valve setting, and I will see if anything has moved, although I doubt it has, because the engine has had this issue with vapour coning out of the carb inlet right from day one.


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## swnf (Mar 5, 2015)

Will follow to see the outcome


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## Charles Lamont (Mar 6, 2015)

Sounds like time for some wilder ideas. Is there a hot spot in the head causing the charge to ignite during admission? Is there a bad earth causing as spark inside the carb?


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