# Opposed Twin I.C.



## Brian Rupnow

I woke up this morning, thinking about an opposed twin i.c. engine. something along the layout of Jason's flat twin Boxter, only a bit cruder perhaps, with an open crankcase and exposed camshafts and crankshaft. I really like the knife and fork style con rod layout, and the fact that it lets the opposed cylinders set in line with each other. I haven't really sorted this through in my head yet, but this would probably mean two camshafts, one above the crank to run the right hand cylinder and one below the crank to run the left hand cylinder.-----Or perhaps both camshafts above the crankshaft, offset to each side. A single centrally located carburetor with long intake runners to each side---maybe. I have to think on this a while.---It feels interesting----Brian


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## dnalot

Im jealous. I always wake up in the morning thinking about coffee and a bagel. 

Mark T


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## Brian Rupnow

This is a new arrangement of connecting rod caps that I have just seen recently. I don't think it holds any real benefit except in a really small sealed crankcase, but it is certainly unique. The "knife and fork" arrangement of the rods lets you run two opposing cylinders in line with each other instead of having to offset them.


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## Brian Rupnow

So---Perhaps we'll rethink this. I am being told that it's very bad juju to  have opposed cylinders going to the same rod journal. I believe the folks who are telling me this. I wondered about it myself, but figured that if it wasn't a good idea somebody would speak up---and they did. I have enough problems with dynamic balance on my single cylinder engines without compounding it. So now--If the con rods go to seperate journals, 180 degrees apart, I can revert to the normal bolt on rod caps.


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## Brian Rupnow

Having been told that "Maytag engines run smooth as silk." I think I will take a page from Mr. Maytags book and start this over again. It appears that the Maytag was a 2 stroke, but having found that there is some serious Voodoo involved with 2 stroke engines, I will be going with 4 stroke, overhead valves.


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## Brian Rupnow

Alright!! ---This is more like it. Thank you Malcolm Stride. Thank you Canadian Cub!!!---This is why we always save our 3D models. I have miles to go before I sleep, but I think I'm on the right track now.----Brian


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## Brian Rupnow

Size looks about right!!


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## Swifty

I'm already following along Brian, I was thinking about a horizontal opposed engine for my next project, not sure if 2 or 4 cylinder yet.

Paul.


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## Brian Rupnow

I have found that by using a 36 tooth and an 18 tooth gear, I can avoid having to cut a jockey gear to fit between them since I don't have the same physical constraints as the original engine. I have to do a bit more modeling to decide whether I like them, or if they will look too big and "clunky".


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## Brian Rupnow

Don't ask me what I'm doing----I'm not sure myself!! Just messing about, modeling, figuring out how I'm going to do this. Right now it's looking like two pieces of aluminum angle, right and left hand bolted together to form the main body, but that may change.


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## jimjam66

Most interesting Brian.  As a long-standing fan of the BMW opposed twin motorcycle engine, I'm inking this one is going to be good! ('Good' in the context of your work means 'even more stellar than usual'.)


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## gus

Brian,

Been waiting for this engine version. OK. I am following on.. Will build this engine too.


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## Brian Rupnow

This is one of those rather unusual cases where, after massive amounts of cutting and carving and rearranging, everything seems to work just fine by bolting two pieces of 1/2" thick aluminum angle together toe to toe. Everything fits, clears, and seems to look surprisingly good. I did lengthen the connecting rods by 1/4" thereby moving the cylinders out 1/4" more from the center-line of the crankshaft to give myself a bit more room. I will make gear covers---Not so much as a safety factor, but as a noise dampner. Those meshing spur gears make a heck of a racket. It would be nice to machine the gear covers from clear Lexan so the gears remain visible but the racket is kept quieter. It appears that the two angles can be machined to finished size, bolted together and dowelled, then drilled and reamed thru both sides in one set-up for oilite bronze bushings for the crankshaft and both camshafts. The angles could then be unbolted to install the crankshaft and camshafts, then reassembled.


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## Jasonb

Brian, one thing to watch and that I still need to sort out on mine is that the crank tends to throw the oil into the right cylinder and oils it up so it does not fire so well. You can feel the exhaust gas from one cylinder is a lot colder than the other but when it does clear itself it romps away.

Either wants a curved baffle plate in the sump to lessen the amount of oil coming into contact with the crank or some thin plates either side of the cylinder opening in the crankcase to stop most of the oil getting to the bore.

This is why the inverted design may be better as the cams won't throw up as much oil and the plugs will be at the top of the heads not the bottom so won't be affected by flooding.


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## Brian Rupnow

Jason--My intent all along has been to run this thing open crankcase---no top on it. Drill oil galleries down thru from the top to the crankcase and camshaft bushings and just give the cams and con rods a squirt of oil on start up.  This engine will never see long duration runs nor heavy service. I want it to run slowly and use a 6 inch diameter flywheel as shown with vanes cut into the outer inch to act as a fan to blow on the cylinders to cool them. This makes for a rather strange looking base but I need that much height in the base to get flywheel clearance.


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## Brian Rupnow

I didn't like that first base---It looked too much like the clock my grandma had on her fireplace mantle!!!


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## Brian Rupnow

So---This is what I would like to do with the flywheel. The flywheel is 6" maximum outer diameter overall x 3/4" thick, made from either brass or mild steel or a combination of the two. The outer band is 1/8" thick The "blades" as I have shown them are 3/16" thick. The outer diameter of the main flywheel body is 4 1/4", and the bore is 3/8". The recess shown in the sides of the flywheel is somewhat irrelevant (I know how to do that.) Now remember--This is a "best case" scenario". I do not have the capacity to machine it from solid. I do have the capacity to cut 3/16" wide slots x 1/8" deep in the outer diameter of the main body to act as "positioners" for the 8 "blades", but the body would soak up so much heat that it would be a real bear to solder the blades in place as individual entities, and that leaves me having to solder or bolt the outer rim into place.--I want the flywheel to be concentric---I hate flywheels that look like they are "orbiting" the crankshaft. I could probably even use #2-56 s.h.c.s. to bolt the blades on, but that's a lot of tapping with a fairly fragile tap. (The head on a #2-56 shcs is small enough to bury in a counterbore in the 3/16" wide blades.)  I'm open for suggestions!!--Brian


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## Brian Rupnow

I have one last piece of bronze left from the government scale checking weight that I was given a couple of years ago. It measures 5 3/4" diameter x 1 5/8" thick. I am so intrigued by the "flywheel with cooling vanes" that I may try to make the flywheel first.  I will have to cobble up some method of slicing it in half. The guy I buy my steel from has a giant bandsaw that he has been using to slice of 1" lengths of this thing for me to make flywheels from, at $10 per slice, but it is now to thin to hold in his saw vice.


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## Charles Lamont

You mention using dowels for the crankcase halves. The halves will have to be brought together in the direction of the crankshaft axis, but your joint lines are in the wrong orientation for this: the dowels would have to be removed to get the thing apart. By having the joints at right-angles to where you have them, the dowel axis can be in the direction of assembly. You would also need to move the joints to the opposite corners so the cylinder flange does not lie over the joint.


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## Swifty

Brian, can an angle plate be held in the bandsaw and the slug clamped to it, cut it halfway throw and reverse.

Paul.


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## canadianhorsepower

Hi Brian

My suggestion is to cut your hole on a rotary table
incline to the degree you want your fins to be

my 3 cents :fan:

good luck


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## Brian Rupnow

Charles Lamont said:


> You mention using dowels for the crankcase halves. The halves will have to be brought together in the direction of the crankshaft axis, but your joint lines are in the wrong orientation for this: the dowels would have to be removed to get the thing apart. By having the joints at right-angles to where you have them, the dowel axis can be in the direction of assembly. You would also need to move the joints to the opposite corners so the cylinder flange does not lie over the joint.


Charles--you are absolutely right. I will look at making that change tomorrow.---Brian ----Swifty---Great minds think alike (Or is it "fools never differ")--That is exactly what I'm thinking of doing. My bandsaw is a converted wood bandsaw and has no feed  mechanism. My big old power hacksaw will possibly do the job If it has enough stroke.


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## Brian Rupnow

canadianhorsepower said:


> Hi Brian
> 
> My suggestion is to cut your hole on a rotary table
> incline to the degree you want your fins to be
> 
> my 3 cents :fan:
> 
> good luck


I thought of that Luc, but I'm not sure I will live long enough to hog out all the material between the fins. It would be a great CNC job though, to just program, set it up, and let it run all night.


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## Brian Rupnow

I've spent the best part of this morning tweaking the model. I had the overlap in the main frame going the wrong direction, so I changed that so the bolts. dowel pins, and crank and camshafts were all in the same plane. I went to a centrally mounted single camshaft, which does indeed simplify things.


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## Charles Lamont

I still think the crankcase joints would be better on the opposite corners which would seem to have less going on.

You might get some ideas from the Mastif flat-4 design by LC Mason:
http://modelenginenews.org/gp/mastif.jpg


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## Brian Rupnow

I already have an "ignition box" containing a standard 12 volt automobile coil, which is wired appropriately with two leads and a high tension wire. It runs in conjunction with an extra 12 volt battery that I have had for years. Since I have 8 or 10 different engines, all single cylinder, with their own points and condensers, I can "plug and play" whatever engine I want into the "ignition box".  I did this because coils are expensive at about $50 each.  i don't want to buy an electronic ignition nor a special coil. I think I can probably make a "splitter box" out of non conductive material which has the coil wire connected to one port, with two separate ignition leads coming out of it, one going to each sparkplug. I see no reason that wouldn't work. Has anybody done that?


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## Brian Rupnow

Okay---now we're at the "what if" stage.--I'm not likely to do this, but IF I decided not to run the engine with an open crankcase, it would be simple to add a couple of gaskets and a top cover. If I ran a cover, then I would need to run some oil in the base for splash lubrication.--As Jason pointed out, this would lead to other issues, with the clockwise rotation flinging oil into the "down-wind" cylinder and loading it up with oil. Really, at this point I'm just "imagineering".


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## gus

I can hear it running from faraway Singapore!!!!


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## Brian Rupnow

gus said:


> I can hear it running from faraway Singapore!!!!


Gus--It certainly makes an interesting model. Nothing really extraordinary there either, because I've built most of the tricky parts before on the Canadian Cub. I think I'm going to buy a new lathe this coming week. It has a 3 year guarantee, but if you read the fine print, the 'labour' part of the guarantee is only good for 90 days. I'm not even going to move the lathe into my machine shop. I will set it up in my main garage and run the crap out of it making all the round parts for this engine. If it doesn't blow up in the first 90 days, then it will probably last forever.---Brian.


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## vascon2196

Wow...is this engine modeled after an old Maytag? Why have I not seen this yet...looks very, very, very cool.


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## Longboy

Brian Rupnow said:


> Okay---now we're at the "what if" stage...... If I ran a cover, then I would need to run some oil in the base for splash lubrication.--As Jason pointed out, this would lead to other issues, with the clockwise rotation flinging oil into the "down-wind" cylinder and loading it up with oil. Really, at this point I'm just "imagineering".


 You (may) not need a splash here, not even for a horizontal cylinder. The WD40 blow by down the cylinders will fling off the crank webs and onto the camshaft. Also a gravity lube reservoir over the cylinders like you see on hit & miss engines looks fanciful. ---     Dave.


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## Brian Rupnow

vascon2196 said:


> Wow...is this engine modeled after an old Maytag? Why have I not seen this yet...looks very, very, very cool.


Chris--you haven;t seen it before because I only started it on Wednesday. It is not a model of a Maytag, Maytags were 2 cycle. However, if you look at post #5, the Maytag layout is my inspiration.---Brian


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## vascon2196

Ahhhh...well I'm glad I stumbled on this. I own 2 Maytag engines and am hooked. I like the look of this engine...your design process is spot on too. I'll be watching until the end.


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## Brian Rupnow

I don't really care for the look of that tall base. Of course, it has to be that tall to accommodate a 6" o.d. flywheel. Really, the working part of the flywheel is only 4 1/4" diameter.


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## Jasonb

Brian, can't you just mount the engine on a wooden display stand and let the flywheel hang down the side?


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## Brian Rupnow

Jasonb said:


> Brian, can't you just mount the engine on a wooden display stand and let the flywheel hang down the side?



Jason--I am considering that.


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## Brian Rupnow

I shortened that base up as much as I could, and I flipped the toes of the angle frame to get my cylinder bases all on one surface. I like the proportions much better this way, although it will have to set up on a wooden base to get flywheel clearance. Dang, I like that flywheel!!!


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## Brian Rupnow

My plan is to have the two cylinders running on opposite cycles. When one piston is coming up to top dead center under compression stroke, the other is coming up to top dead center on exhaust stroke. That way I get a power pulse every 360 degrees of rotation.-----Brian


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## barnesrickw

Brian, you mentioned some "voodoo" when talking about the timing on the two cycle Maytags.  I remember when researching Saab 2 cycle, three cylinders, there was some voodoo involved there.  I would like to figure that out someday.


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## Brian Rupnow

barnesrickw said:


> Brian, you mentioned some "voodoo" when talking about the timing on the two cycle Maytags.  I remember when researching Saab 2 cycle, three cylinders, there was some voodoo involved there.  I would like to figure that out someday.


Jan Ridders seems to have success with the two stroke engines he builds and runs. Everybody else I have ever heard from who built his engines to spec  had a horrible time getting them to run. Many, perhaps most of them ended up holding down shelves as nicely executed ornaments.


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## Brian Rupnow

I resorted to a little hocus pocus when I designed the bushings for the crankshaft and camshaft. I wanted to be able to pull the crankshaft or the camshaft straight out of the engine  without splitting those two main frame angles. So---I have a large "bushing insert" with the bushing pressed into it, bolted into a counterbore in the frame angle which supports the end of the crankshaft closest to the flywheel. If I remove the flywheel and the blue "bushing insert" the entire crankshaft  should pull straight out through the side of the housing. I did something very similar at the opposite end of the camshaft, only there the bushing itself has a large enough outer diameter that by unbolting it and pulling it out, the whole assembled camshaft can be pulled out thru the side of the main frame.


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## Longboy

......still looks pretty tight inside the crankcase. You are not showing accessibility with a sealed angle frame to disconnect rod caps from crankshaft to then pull the crank from the frame........without unbolting the frame segments. With an opposed engine, you have to come in from both sides for the caps! I really don't see using a pair of bolted angle pieces as a frame as allowing this engine to assemble or service.  -----Dave.


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## Brian Rupnow

Longboy--It is VERY tight. the only redeeming point is that if I unbolt the baseplate, I have access from top and bottom to get at the con rod bolts.


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## Longboy

Yes!..... I'm seeing you have a blind right angle access to the cap bolts in a tight space and not much room to turn a wrench....this doesn't look good.


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## Brian Rupnow

Longboy said:


> Yes!..... I'm seeing you have a blind right angle access to the cap bolts in a tight space and not much room to turn a wrench....this doesn't look good.


God works in mysterious ways----and so do I!!! Thank you for noticing and commenting. I may have to use my flexible Allen wrench.---Brian


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## Jasonb

Brian yours has a much room as my crankcase and I can get at the bolts. You also have the advantage of an open top and bottom mine is closed in on 5 sides.

With the cylinder and liner removed the conrods drop to about 40 degrees so access is quiet easy, run them in with a ball ended hex screwdriver and nip up with a standard key

With no top on your crancase the upper bold is straight acces, the lower works with the ball ended tool and you can swing an L shaped hex key with no problem


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## Brian Rupnow

Jasonb said:


> Brian yours has a much room as my crankcase and I can get at the bolts. You also have the advantage of an open top and bottom mine is closed in on 5 sides.
> 
> With the cylinder and liner removed the conrods drop to about 40 degrees so access is quiet easy, run them in with a ball ended hex screwdriver and nip up with a standard key
> 
> With no top on your crancase the upper bold is straight acces, the lower works with the ball ended tool and you can swing an L shaped hex key with no problem


Thanks Jason--I knew that.


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## Brian Rupnow

Well, noooo---We don't really know what we're doing.--But--we're having fun. Gotta have some way to get fuel into those cylinders.


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## gus

Hi Brian.

Can we run with glow plugs to save the hassle with ignition timing??? Some 4 stroke OS engines are glow plug fired.


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## Brian Rupnow

Gus---I have never used glow plugs and I don't know anything about them. I think they only work on two cycle engines but I may be wrong.---Brian


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## Brian Rupnow

I'm thinking that makes a rather nice fuel tank. It is 1" o.d. x 3 1/2" long. It is supported off the carburetor bracket. (Don't ask me exactly how yet), and the top of it is about 1/4" below the center of the carburetor barrel. It does clear the flywheel.


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## Brian Rupnow

A slight change to the "magic flywheel". I have noticed at my metal supplier that they frequently have offcut "donuts" of 660 bronze. This one measures 4.1" o.d. x 2.76" i.d. z 1.1" thick. The 3" square piece of aluminum is also an offcut. I get offcuts for half the price of new material, because they don't charge for a mans time to pull material out to the saw and cut it off. The bronze will of course be the main weight of the flywheel rim. The aluminum will be set up in my 4 jaw and turned to become the center hub. The brass bar will become the "vanes". I haven't got the material for the outer band yet, but it will probably be thin wall steel tubing.


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## gus

Will follow the FanWheel fabrication.


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## Brian Rupnow

I don't plan on boring you to death with a thousand pictures of "How to build a flywheel.", but this rim has a special place of honour.--It is the very first piece ever made on my new lathe.


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## Brian Rupnow

I chickened on the flywheel center material. A 1" long slice of 3" round aluminum stock was only $5 and the 1" long outer rim part was $5.  I will save the 3" square piece of aluminum and use it for something else.


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## gus

Hi Brian,

The new lathe performing well??? I am drooling but have to bear in mind I have limited space.


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## Brian Rupnow

Yes Gus, it is performing very well. I am as nervous as a cat in a roomfull of dogs while running it, but it has performed every task very well. I stalled it this morning taking trepanning cuts on the center of a  flywheel. It didn't like that very much, ---Just stopped turning and gave a very angry hum. I hit the e-stop, backed out the tool and started the lathe again. No harm, no foul.--scared me though!!! The trepanned recess is 1/4" deep. I tried to plunge the full depth in one shot just to see if I could.--I couldn't. So plunged .100 deep closet to the center, then plunged .100 deep closest to the rim, then used crossfeed to move back and forth between the two annular grooves taking .010" deep cuts until I had a flat bottomed recess, then plunged 0.100' again at inner and outer extents, repeated the back and forth, then a final plunge of 0.050" and travel back and forth removing .010" on each cut until I ended up with a flat bottomed 1/4" deep recess.


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## Brian Rupnow

The flywheel center is finished except for keyway and set screws. I am going to try my hand at heat shrinking the bronze outer rim onto the aluminum center. I have only .003 to .004" interference, and could most likely press it in cold. Mrs Rupnow wouldn't take very kindly to me heating up the bronze ring in the kitchen oven, so I will leave it under my big heat light overnight and keep the aluminum center in the freezer overnight and see what happens. I'm not ready to assemble them yet. I have some very strange and devious things to do to that bronze ring with my milling machine and rotary table to prepare it for the eight cooling vanes, and I need to leave the center open to grip with the 3 jaw chuck fingers on my rotary table.


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## Swifty

I'm a great advocate of shrink fitting, but I would only use about .001" to .002" interference on a part that size. suggest to your wife that she makes an apple pie, and when she is not looking, put the ring in the oven

Paul.


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## petertha

Brian Rupnow said:


> Gus---I have never used glow plugs and I don't know anything about them. I think they only work on two cycle engines but I may be wrong.---Brian


 
Glow plugs have been standard fare RC 4-stroke engines for must be approaching 40 years now. Glow plugs are intended for "glow fuels" (methanol/oil premix). 4S glowplugs are same principle as 2S plugs, but slightly different wire (temp) & other properties.
http://www.osengines.com/history.html
http://www.osengines.com/engines-airplane/index.html


..but something I didn't know until recently, 1/4-32 plugs for gasoline RC engines.


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## Brian Rupnow

This vaned flywheel is getting more and more interesting. I'm kind of making it up as I go along. I'm pretty sure I can set the rotary table at 45 degrees to the long axis of the table, mount the bronze ring on the 3 jaw chuck holding it from the inside  and using a 3/16" endmill  run the table back and forth in X axis to cut the slots 3/16" wide x 1/8" deep. Then drill and tap the  two #2-56 holes in the bottom of the slot.--Then rotate the rotary table 45 degrees and repeat---eight times in total. The vanes would be from 3/16" x 7/8" flatbar, drilled and counterbored for #2-56 socket head capscrews. The end of the flatbar closest to the center would just be a flat 90 degree cut. The cut at the other end however, will take on a strange twisted shape if it is going to be full contact with the inside of the outer rim. They will be brass, so MAYBE I can cut them .050" long, then bolt them to the bronze hub, press in the center, and then take a skim cut on the outer ends of the flatbar with the lathe to bring them down to final size.


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## barnesrickw

Could you have used an old computer cooling fan if you didn't want the pretty version?


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## Brian Rupnow

barnesrickw said:


> Could you have used an old computer cooling fan if you didn't want the pretty version?


Yes, I could have----if. Right now I have two or three i.c. engines I have built and posted on this forum about that run either small plastic fans or fabricated brass fans, driven by an o-ring drive off the flywheel. I have my heart set on this "pretty" version, but it may not happen. I can see my way clearly up to the point where I have to attach the outer rim. That is problematic. I may make up everything but the outer rim. That would create a dangerous finger chopper, But--If I ran it in a close fitting "fixed" shroud it would still have the same effect in terms of creating airflow over the cylinders, be safe in terms of chopped fingers, and be one heck of a lot easier to fabricate.


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## Brian Rupnow

Okay---Maybe I'm onto something a little more realistic. The flywheel with vanes revolves--the outer rim has become a fixed shroud. Much, much easier to fabricate.--Finger safe, and still provides cooling air.


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## barnesrickw

I like the separate rim/shroud idea if interested in protecting fingers.  I'm of the school of "don't put your fingers there", but that has backfired on me.


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## gus

I have seen Ingersoll-Rand air compressors coming into Singapore in the 60s 70s with Open BeltGuard,Semi-Enclosed B Guards and fully enclosed BGs and all not finger proof. In the 80s 90s 00s all BGs were finger proof. There were some native workmen South Africa who would poked their fingers thru non-finger proof BGs  to claim big compensation. Gus would never work on compressors with BGs removed. Just very scary.

HMEM folks.Please take care.


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## Brian Rupnow

Making it up as I go along---the rotary table mounted at 45 degrees to the X axis on the mill and a 1/8" four  flute endmill did the job just as I hoped it would. The slots are 3/16" deep x about .130" wide. While in the same set-up I drilled 1/16" holes thru on center of each slot. I then Loctited 1/16" cold rolled round rod x 1" long into the holes, with 1/2" exposed. I made up the 8 "vanes" from 1/8" thick aluminum and drilled a blind  1/16" hole 0.7" deep in the center of each "vane". I knew that the .125" vanes were not going to fit tightly into the 0.130" wide slots----but I had a plan. After trial fitting everything, I got out my old friend J.B. Weld, mixed up a batch, and filled one groove at a time and coated the exposed portion of 1/16" cold rolled, then tapped the vane into place until it was seated.  Right now the bronze ring and the aluminum hub are both 1/8" wider than the planned 3/4" finish width. It is my greatest hope that after Loctiting/pressing the aluminum hub into the bronze ring (I have decided not to use heat shrinking) that I will be able to grind a really sharp tool and face both sides of the aluminum center, the bronze ring, and the sides of the vanes without everything turning to crap.


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## vascon2196

That is a really neat way to make a flywheel with vanes...awesome.


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## Brian Rupnow

Here we are at the lumpy nasty stage. The vanes are secured with a large pipe clamp. The aluminum hub is a "Damn that's close/Loctite fit". After a night of curing, it will be into the lathe and either be the "Oh Wow--Look how good I am" stage or the "Oh Poop!! Start over again" stage.


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## Brian Rupnow

Machining of flywheel with vanes attached went very well. The vanes never gave any indication that they might want to come off. The biggest challenge I had was that 660 bronze hub wanting to suck the tool into the work while facing it. I am putting this down to the fact that the shaft everything was mounted on was only 3/8" diameter, and once the tool tried to suck into the bronze the shaft would deflect a bit, then spring back, leaving a series of evenly spaced divots around the face of the bronze. I tried every machine speed and tool angle and sharpness, but nothing made any difference. Thankfully the divots were shallow enough to mostly come out with some 160 and 220 grit emery cloth. The aluminum vanes of course came out razor sharp, but some light file work knocked the sharp down a bit. I definitely won't be running this flywheel without a full surround shroud.


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## MRA

Brian Rupnow said:


> I resorted to a little hocus pocus when I designed the bushings for the crankshaft and camshaft. I wanted to be able to pull the crankshaft or the camshaft straight out of the engine  without splitting those two main frame angles. So---I have a large "bushing insert" with the bushing pressed into it, bolted into a counterbore in the frame angle which supports the end of the crankshaft closest to the flywheel. If I remove the flywheel and the blue "bushing insert" the entire crankshaft  should pull straight out through the side of the housing. I did something very similar at the opposite end of the camshaft, only there the bushing itself has a large enough outer diameter that by unbolting it and pulling it out, the whole assembled camshaft can be pulled out thru the side of the main frame.



Hi Brian
I stumbled across your post, and thought you might like to know that this is just how the crank goes in / out of a flat twin motorbike engine (with con rods in-situ) - but I guess that's where you got the idea from.  I run a 70s 'Ural' 650cc bike made in Russia, which looks a lot like a BMW (for historical reasons I won't bore you with).  I bought it in big rusty lumps with a seized big end, and even with the rear main bearing carrier plate removed, the seizure meant the con rods wouldn't fold up (to BDC) to allow me to roll the crank out through the resulting aperture.  Lots of unsympathetic con rod bashing with a big hammer was the only way forward


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## ICEpeter

Hello Brian,
Like your design work and in particular your opposed twin IC design. Want to raise a point though about the way you made or rather attached the vanes to the fan wheel / fly wheel center using a combination of JB weld and some 1/16" dia. pins.

I know the rpm of the engine will be low but I have a concern about the limitations of the retaining forces that will try to restrain and hold in place the vanes against the centrifugal forces that will try to pull the vanes outward. I don't know how well the JB and the 1/16" pins will be able to do that short or long term since the centrifugal forces apply in shear to the JB weld / vanes and 1/16" pins.

Instead of having the shroud a separate piece of the fan / fly wheel I believe it would add to safety by making the shroud an integral part of the fan assembly. 

Like your work and creativity!

Peter J.


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## Brian Rupnow

Peter--Your concern is noted. I was going to attach the outer rim to the vanes, but simply couldn't come up with any good way of doing it. The vanes are only 1/8" thick. I have no concerns about the Loctite in shear. The JB Weld I'm not so sure about, but the end of the vanes are only 0.100" from the inside of the stationary shroud. The flywheel is only 3/4" thick, the shroud will be the same width.


----------



## Brian Rupnow

Now that, my friends, is a piece of angle!! I had to go across town yesterday to pick up some Destaco clamps for a customer project, and one of my metal suppliers is almost next door. I stopped in and asked if he had any offcuts of aluminum angles with 1/2" thick legs. He answered "Yes, and I've been saving it just for you!!!"---It is a piece of aluminum angle 8" x 8" x 1/2" x 10" long. Far more than I need, but there is a lot of good 1/2"  material that I can salvage from it after I cut out what I need for the engine frame.


----------



## Brian Rupnow

I haven't abandoned this project.--It's just that I've been so busy with other projects----. Tonight I stole an hour to add all the bolt holes into the two main frame angles and show the four 1/4"-20 bolts (green-two each side) that hold the angles together.


----------



## Brian Rupnow

After a summer of "relative" idleness, my business commitments have exploded to the point where I have no time to build my own stuff!!! I did steal some time this afternoon to walk out to my converted bandsaw with that HUGE chunk of aluminum angle, and reduce it to smaller pieces, close to what my engine's finished frame size will be.This great flurry of real work will only last for a couple of months and then die down just before Christmas. After the struggle I had unloading and setting up my new lathe by myself, I decided to call a local machinery moving company and ask for a quote to move my old lathe out from my machine shop into my big garage, and move my new larger lathe from my big garage through my office into my small machine shop. They quoted $500 which seems like a lot, but I think some of the money from my current "real work" would be well spent having them do this. Both lathes are quite top heavy, and if I tipped either of them over while moving them, that $500 wouldn't seem like very much!!!


----------



## gus

Hi Brian,

Paul Swift,
Received a call at 5.45 am  and going for Kidney Transplant. Please pray for successful operation.


----------



## Brian Rupnow

Paul has my prayers and best wishes.---Brian


----------



## Brian Rupnow

This morning I have made the unsettling discovery that aluminum angles aren't really 90 degrees on the outside. In fact over a 2 1/2" leg. they run out as much as .030". I can clean this up, it's not a deal breaker, just a surprise. I wonder how much things will spring out of square when I machine away that rolled in inner radius? I think I will get rid of the inner radius first, see where things spring to, then clean up the squareness.


----------



## Brian Rupnow

So there we have it. An absolutely fabulous way to spend a Saturday. The frame pieces are cut to size, the radius is machined away, and the main frame bolts and dowel pins are in place.


----------



## ICEpeter

Brian,
I may look at it wrong but it appears to me as if there is a slight misalignment of the angle piece at the upper corner facing towards the viewer when looking at the picture?

Peter J.


----------



## Brian Rupnow

Peter-It's not your eyes. I haven't completely finished the two pieces yet. They are machined and bolted together, but I still have to take a very light "squaring cut" to make all sides square and parallel. The problem with making pieces like this in a milling vice is that the jaws always "cock up" one or two degrees when closed under pressure, and the results quite often are what you see. For a squaring cut" the assembly gets clamped to the mill table with a pair of toe clamps, which ensures that all faces end up square and parallel to each other.---Brian


----------



## RonGinger

To help prevent pieces from 'cock up' in a  vise use a round rod between the movable jaw and the work. This makes it a line contact and forces the work against the fixed jaw.


----------



## Brian Rupnow

RonGinger said:


> To help prevent pieces from 'cock up' in a  vise use a round rod between the movable jaw and the work. This makes it a line contact and forces the work against the fixed jaw.


I will certainly try that Ron---Thank you.


----------



## Brian Rupnow

Yes, Me darlin's---Any progress is better than "dead in the water"!! I got hung up this afternoon waiting for information from a customer, so I spent my time making the big "bolt-on" crankshaft bushing and drilling/reaming/boring the engine housing to fit it. Don't take me to task to heavily for the finish on that big bolt on bushing. It was machined from a piece of "mystery metal" with a carbide cutting tool of dubious origin. (I was given a big handful of brazed carbide tooling by a fab shop that has switched over to carbide inserts.)---it isn't going to be visible anyways, as it hides behind my finned flywheel when all is assembled. I have a jar of oilite bushings left over from something, and that is what you see pressed into the center of the bolt on bushing. No, that isn't the crankshaft you see setting in there---It's just a short piece of 3/8" rod to make a better picture.


----------



## Brian Rupnow

On the side of the frame opposite to the bolt in crankshaft bushing, I also wanted to have a "bolt in" camshaft bushing, large enough to let me pull the assembled camshaft out through the side of the frame. This results in some rather interesting milling, (than God for my DRO's). The sheet of paper laying in the background shows a model of what the cam bushing will look like. ----(scale is larger than the real deal, but it shows up better). The through hole in the frame is reamed to 0.5" diameter and the protrusion on the far side of the cam bushing will be 0.499" diameter.  The reamed hole in the center of the red cam bushing is .375" diameter to match the outer diameter of the oilite bronze camshaft bushing. The odd shaped cavity in the frame will be clearance all around for the outer perimeter of the cam bushing, and the cam bushing will be held in place by two #8 shcs.


----------



## Brian Rupnow

This has to be one of the busier pieces I have made. (Actually, it's two pieces bolted and doweled together). It has: 30 tapped holes, 4 clearance holes, 21 reamed holes, one bored hole, and one counterbored pocket.  I THINK they are all in the right place. I have been very busy with design work, moving lathes, and repositioning electrical outlets and the associated drywall work to accommodate the new lathe in my tiny machine shop. The old green 10" x 18 BusyBee lathe and all its attachments has been sold and taken away to a new home in Toronto.


----------



## Brian Rupnow

I don't plan on ever taking it apart. The crankshaft and the camshaft can be installed through the side of the frame. Hindsight being 20/20, if I had to do this over again, I would probably make it from a cube of aluminum. The only issue would have been cleaning out the rad in the four inside corners.


----------



## Brian Rupnow

Out with the old----In with the new!!! The new CX701 lathe is installed in my machine shop ready for action. I had to relocate one electrical outlet and repair a bit of drywall, but other than that everything went very well. I have a piece of 2" x 1/8" mild steel bar welded into a U shape. It bolts to the studding in the wall and both ends are bolted to the cabinet which supports the lathe. The lathe is bolted through the catch pan and through the top sheet metal of the supporting cabinets. This just gives me that extra bit of security so I know that the lathe and stand is not going to ever fall over.


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## 10K Pete

What? Worried about earthquakes Brian?? 

Pete


----------



## RonGinger

Years ago I made a rotary phase converter for my shop. I thought it would be nice to get the motor up off the floor so I bolted it into the wall. That turned the whole shop wall into a drumhead and the noise it made was unbelievable. it was back on the floor as fast as I could move it.  I am not sure bolting tools to the wall is a good idea.


----------



## Brian Rupnow

Ron---I find just the opposite. Being bolted to the stud walls in my basement actually makes my mill and lathe quieter.


----------



## Brian Rupnow

One cylinder machined this morning.--One more to go this afternoon!!! They are cast iron, not aluminum with a liner.


----------



## Brian Rupnow

As my old father-in-law used to say "It ain't perfect, but it's damned close!!!" This project has been stalled for so long, I just had to take some time to do something for ME for a change. Today while I was working on the cylinders, another order for more "fixtures" came in so I know what I'll be doing the rest of the week, and it isn't working on my engine. It is very interesting to actually do some work on my new lathe. It is miles different from my older smaller lathe, and I will have to work with it quite a lot before I become comfortable with it. I did use the power feed to bring the cast iron down to correct diameter, and it certainly leaves a beautiful finish.


----------



## Fatboyfinn

After building a "Firefly 46" which came together very nicely, I had a desire to build a multi- 
cylinder engine. So, a twin Firefly... a horizontally opposed two stroke, simultaneously  firing.
Apparently very smooth and vibration free. I decided to fabricate the crankshaft, fitting the conrods during assembly .I think I might pin the crank-pins, just in case.   This meant building a split crankcase with a rear bearing . I had an idea to install the needle valve in the back bearing plate. Anyway, so far so good ...


----------



## Brian Rupnow

After what seems like an amazingly long time I finally got some time today to do a bit more work on my engine. I drilled all the clearance holes in the flanges which attach the cylinders to the "block" and installed the bolts. Everything bolted up the way I expected it to, and then I drilled the 10 holes (five in each cylinder) that get tapped #5-40 to hold the cylinder heads onto the cylinders. When I was tapping the eighth hole, the tap broke off at full depth flush with the top of the cylinder. --This caused a great deal of dismay as you can well expect, but after picking away at it for a while with no success, I chucked up a 1/16" carbide endmill and was able to mill out the tap and save the cylinder. I have a length of "stress proof" 1144 steel to make a one piece crankshaft from, and will probably make that my next order of business.


----------



## Brian Rupnow

Today was "crankshaft madness day" at my house!! I wanted to buy a piece of 1 3/8"  1144 stress-proof to make my crankshaft from. 1144 is not available to buy in bars, only rounds.--and my supplier only had it in 1 1/2" diameter. The first two pictures show me reducing the stock from 1 1/2" diameter to 1.3" final diameter.--And yes, I did use the power feed for this operation, with an HSS cutter at 550 rpm. Also, in the same set-ups I put in the 60 degree countersink in each end so I can eventually turn the crankshaft between centers.


----------



## Brian Rupnow

After turning the piece to 1.300" finished diameter, I had to get it from a round into a flat. I thought of various ways to cut away most of the slab from each side on my bandsaw, but any good way was going to involve me building some kind of fixture, so I decided to mill the excess material away.  My thoughts in using the rotary table chuck to hold the part for this machining operation, along with the tailstock, was that this was probably the set-up that gave me the best hope of getting flat parallel surfaces and being able to flip the part over a true 180 degrees to machine the second side away. It worked, but at a .015" depth of cut there was a LOT of cranking involved. I have cut the blank to be 3/4" longer than the finished length of the crankshaft, so I figured I would probably be safe in holding 3/16" of the piece in the chuck on the rotary table, mounted on my mill.


----------



## Brian Rupnow

All of the preceding operations have brought me to the point where I may actually be able to start machining the crankshaft. The first operation will be to put in two more countersunk holes in each end to provide a spot for turning the crank "throws" between centers.


----------



## canadianhorsepower

Brian Rupnow said:


> Hi Brian
> 
> just wondering :hDe: you don't believe in the x3 rule
> in a lathe
> 
> cheers


----------



## 10K Pete

canadianhorsepower said:


> Hi Brian
> 
> just wondering :hDe: you don't believe in the x3 rule
> in a lathe
> 
> cheers



What's the x3 rule? Never heard of it. 

Pete


----------



## Cogsy

I think he means you're only supposed to have a maximum of 3 x the diameter out from the chuck unsupported. I must admit I stretch this rule regularly, but then I don't take production depth cuts at production feed rates so I figure I can get away with it.


----------



## 10K Pete

Cogsy said:


> I think he means you're only supposed to have a maximum of 3 x the diameter out from the chuck unsupported. I must admit I stretch this rule regularly, but then I don't take production depth cuts at production feed rates so I figure I can get away with it.



Ahhh, never heard of that before but I guess there is a ROT for most
anything. My rule is that if it's rigid enough to make a cut, I do it! Actually I do
have a rule: The part must never come out of the chuck on it's own.



Pete


----------



## gus

Cogsy said:


> I think he means you're only supposed to have a maximum of 3 x the diameter out from the chuck unsupported. I must admit I stretch this rule regularly, but then I don't take production depth cuts at production feed rates so I figure I can get away with it.




Hi Cogsy. Thanks for the thumb rule. Been taking risks with longer extensions but when I have the gut feeling , I shorten extension or take like cuts or end up with centre supports.


----------



## Brian Rupnow

Since I distinctly remember making a beautiful one piece crankshaft a few years ago between centers, and then discovering to my horror that the lathe tailstock was way out of alignment, I thought some checking was in order. The lathe tailstock "as delivered" from the factory was out---not much, but not dead nuts either. I did a google search last night and discovered a Youtube video of aligning the tailstock with a co-axial indicator. This morning I set things up as shown in the video, and adjusted my tailstock side to side as close to zero indicator reading as I could get it. Now before anybody jumps on me with both feet, I know this doesn't truly align the spindles. However it does align the rotating centerline of the chuck with the centerline of the tailstock spindle. The TIR of the chuck is very little.--It will be close enough to accomplish what I am planning to do.


----------



## Brian Rupnow

Today I removed the chuck and mounted the faceplate on my new lathe, put the dead center in the headstock spindle, and made a couple of discoveries. First discovery was that the two lathe dogs I bought 6 years ago with my first lathe and never actually used, won't work with my new faceplate. Second discovery was that although I bought a "live center" when I bought the lathe a few months ago, it has dissapeared. In fact I don't ever remember seeing it since I bought the lathe. Of course, this raises the question, ---Did I ever actually get one and bring it home? (It is on the invoice which I still have.) ---or---Did I pay for it but it was temporarily out of stock and they were going to order it in from Toronto for me. I will talk to the Barrie store tomorrow and see what they know. I've had so much machinery coming and going around here in the past six months that almost anything is possible. I still haven't totally sussed out my tailstock alignment, but have decided that if I am going to do this right, I might as well do it  between centers, and since I plan on machining the crankshaft between centers anyways now was a good time to get the faceplate mounted and to take the four jaw chuck out of the packing box and make sure it was okay. I keep my shop and garage fairly well organized---It is very unusual for me to misplace a piece of tooling. It is especially suspicious when I never remember even seeing the live center. I will build a couple of "custom fit" lathe dogs this week to work with the crankshaft.


----------



## Brian Rupnow

canadianhorsepower said:


> Brian Rupnow said:
> 
> 
> 
> Hi Brian
> 
> just wondering :hDe: you don't believe in the x3 rule
> in a lathe
> 
> cheers
> 
> 
> 
> Luc--I don't think I ever heard of that rule before. If it means that you mustn't have the part stuck out from the jaws more than 3 x the diameter, then I was probably okay. The total length of stock is 6 1/2" and the diameter is 1.5" to start with. I machined half the length down to 1.3" diameter, then flipped the part "end for end" and machined the other half. There was never more than 4" of material stuck out past the jaws.---Brian
Click to expand...


----------



## Jasonb

3x rule does not apply here as Brian had Tailstock support. 

If  the rule was for when using tailstock support you would never turn anything long.


----------



## Cogsy

Jasonb said:


> 3x rule does not apply here as Brian had Tailstock support.


 


He only used the tailstock on the mill, I think Luc was talking about the lathe where he wasn't.


----------



## Brian Rupnow

It looks like the first order of the day will be to make up a couple of "custom" lathe dogs to use when making the crankshaft between centers. These will be welded up from some scraps out of my steel "odds and ends" pile and saved as "future tooling".


----------



## raven007

The engine looks great. You will however need to implement a distributor of some sort. One single ended coil feeding two plugs wont work as the electricity will follow the path of least resistance and only fire the plug not under compression. Alternately look into a motorcycle coil with two high tension leads. One from an older Harley or Honda CB (twin or four cylinder, you would only need one from a four) should work fine.


----------



## canadianhorsepower

raven007 said:


> One single ended coil feeding two plugs wont work as the electricity will follow the path of least resistance and only fire the plug not under compression. .



Your quote is half wrong:wall: you are wright about the path following
the least resistance, BUT the lest resistance is the one with a gas mix.
It's called Lost Ignition and this is how all distributor-less cars truck>>>>>> are working 
cheers


----------



## raven007

Suit yourself, no matter how wrong you may be. 

But wasted (lost as you say) spark systems use a coil without one end of the high voltage grounded. Rather, both plugs complete the circuit. Feel free to google it. Cheers.


----------



## johnny1320

waste spark on a two cylinder with one coil uses the two plugs at each end of the secondary windings one plug is ground one is pos.


----------



## canadianhorsepower

raven007 said:


> But wasted (lost as you say) spark systems use a coil without one end of the high voltage grounded. Rather, both plugs complete the circuit. Feel free to google it. Cheers.



I'm not trying to have an argument here but simply give information
that was explain to us at GM training plant, "I'm a Grand Master Gm certified"
have a look at this  enjoy

https://en.wikipedia.org/wiki/Wasted_spark


----------



## johnny1320

Been drag racing motorcycles for 28 years and we use waste spark setup and with one coil doing two cylinders. I run two coils for 4 cylinders and secondary windings are as raven007 stated.
Have a look at the diagram on your link. It illustrates exactly what we are saying


----------



## canadianhorsepower

johnny1320 said:


> .
> Have a look at the diagram on your link. It illustrates exactly what we are saying



I guess it's lots in translation Rof}Rof}
we both agree on the same pictures but explain it differently 
Maybe being a freshmen and explaining thing in English is not a good IDEA 
cheers

 *beer**beer*


----------



## johnny1320

Your talking about two different things, a coil sharing two leads is not the same as a coil with dual outlets, the spark plugs on a dual outlet coil with spark at the same time, not so with a siamese connection which only the plug with the least resistance will fire which most likely will be the cylinder on exhaust due to the cylinder under pressure makes it harder to jump the gap. I don't know why you have to be insulting when someone disagrees with you canadianhorsepower?


----------



## canadianhorsepower

johnny1320 said:


> Sorry Johnny1320,
> not trying to insult anyone, as I said we both agree on the diagram but could not explain it properly in English


----------



## raven007

Its cool on my end. No worries.


----------



## Brian Rupnow

After what seemed to be far more struggle than I anticipated, the tailstock alignment is correct within .001" of being the same as the center in the headstock spindle. I ended up machining two ends of a bar held between centers and adjusting the tailstock until I was getting micrometer readings within .001" of each other at each end, and said "That's it!!!".  I made a lathe dog to drive the bar that was held between centers, and was really surprised how much it threw the lathe out of balance. I would have liked to run the lathe at 800 rpm to get a really good finish on the two areas I turned, but at anything over 350 rpm the lathe wanted to levitate. I will have to add counterweights to the faceplate when I turn the crankshaft between centers using a lathe dog.


----------



## johnny1320

I'm good too. thats the problem with typing things get miss interpreted.


----------



## Brian Rupnow

Okay--we forge onward here, adding to our list of what seems to work and what doesn't. I now know that the 4 jaw chuck is complete and does indeed fit the spindle. The faceplate is a beautiful thing, and it fits alright, but it throws the lathe out of balance at anything over 400 rpm., even without any lathe dog. I take it from that that the faceplate casting itself is out of balance. Changing the 3 jaw chuck (which does seem to be in balance) for the faceplate (which seems to NOT be in balance) is a pain in the arse!!!! I now see the wisdom in just chucking up a piece of roundstock and turning a 60 degree point on it to make a center at the headstock when I want to turn something between centers. Doing this will allow me to use a much shorter, and therefore more balanced lathe dog as well.


----------



## Brian Rupnow

So---Maybe a lathe dog with a more balanced approach---


----------



## Brian Rupnow

And here we have the latest in "Extreme low tech lathe doggery". Drill and tap one leg of a very cheap machinist clamp for a quarter inch bolt. The designer liked his fancy design, but the machinist said `Whoa---Too much work!!!` I will put a tie-wrap around the shaft and thru the arms of the machinist clamp `just in case`.


----------



## canadianhorsepower

Brian Rupnow said:


> I will put a tie-wrap around the shaft and thru the arms of the machinist clamp `just in case`.


Hi Brian
IMHO 
nice workI would have the shaft end Round and prick punch the offset  and run with a dog leg

Or do what you are doing using your mill , That crank is flat Out  so you can go 
0,180, 0 to machine everything 

nice work


----------



## Brian Rupnow

Well---Maybe it's not up there with sky-diving, but it sure makes my old heart go "pitter-patter"!!!! I'm running at 200 rpm.--Standing well to one side of potential "flying bits". First rod journal is cut to correct width but needs a clean-up to get the diameter down from 0.430 to 0.375". Probably nothing to it for all the "old time machinists" out there, but it scares the Bejeezuz out of me.


----------



## Charles Lamont

I'd advise roughing out all over (leaving lugs with throw centres in at the ends, obviously) before finishing any dimension.


----------



## Brian Rupnow

Charles Lamont said:


> I'd advise roughing out all over (leaving lugs with throw centres in at the ends, obviously) before finishing any dimension.


Charles--I hadn't really thought about that. The only problem I see with it, is that it would become very difficult to turn the ends down. I'm not even really sure how you would go about doing that unless you plunge cut with a parting off tool out at the ends.


----------



## Brian Rupnow

Charles--I think this is what you mean. This photo was posted on another forum I post on by Jason, a gentleman from the U.K.  The piece I am currently working on isn't long enough to allow for this.---Brian


----------



## Cogsy

I assume Charles suggested roughing it all out to allow for any stresses in the steel to show themselves, then final machining to size would eliminate any distortion that had occurred. As you're using 1144 stressproof it shouldn't matter. My Peewee V4 crank didn't seem to change at all as it was machined.


----------



## Charles Lamont

Brian Rupnow said:


> Charles--I think this is what you mean. This photo was posted on another forum I post on by Jason, a gentleman from the U.K.  The piece I am currently working on isn't long enough to allow for this.


Brian, yes, that is exactly what I mean. After the crankpins are finish turned you cut the lugs off (with a hacksaw) and finish turn the main journals between centres (with distance pieces between the webs, if you like). I don't understand what you mean when you say your part is not long enough.


----------



## Jasonb

Brain you don't cut the whole of the block at the end away, just enough to leave a square that is then turned down as part of the main shaft.

This is finished length

Roughing






Part way through, front waste material removed and test fitting bearings, waste still on teh back end. Note ctrs also drilled and tapped so a stud can be screwed in to drive the crank against a chuck jaw
















Finishing the other end


----------



## Brian Rupnow

Tomorrow morning I get to the "extreme breath holding" part of this----The "sides" of the rod journal are turned to their finished width, but I have to turn the journal diameter down to it's finished size. On my old lathe, I would have set up my "carriage stops" on both limits of travel to keep the sides of the crankshaft from whacking the top of the parting tool and creating instant disaster. On my new lathe, I don't have any real good way of setting up "travel limiters" on the topslide (Which I have set up parallel to the ways and can still thankfully advance by hand.) This will be a "Stand well to one side and move the topslide REALLY SLOWLY" sort of deal.


----------



## Brian Rupnow

Here we have finished rod journal #2. Everything is right on spec. and turned to final size. I have a "perfectly fitted" aluminum spacer in the gap where I cut the first journal from, to keep the crank from deforming under the pressure of the lathe "centers". It is held in place with glue from a glue gun---See---I do learn things from these forums!!!  This second journal wasn't quite as scary as the first one, but you certainly don't want to let your mind wander while doing it!!!  It really helps my peace of mind knowing that I actually do have a carriage lock on this lathe. (Which I just found out about this morning when I logged on and read my forum mail.) I will now glue a spacer in this new gap and then proceed to find my way through turning the ends down.


----------



## Brian Rupnow

This morning I turned the first main crankshaft journal, and discovered a dirty little secret. I have suspected all along that it would be almost impossible to set the topslide perfectly parallel to the ways. You can get it super close with a dial indicator, but I still didn't totally trust it. I confirmed that this morning by turning the crankshaft journal down over it's full 2" length using the topslide only, with the carriage locked, but I left the journal a bit  oversize. I then measured both ends with a micrometer, and sure enough, I was turning a very slight taper. Having established that, I locked the topslide and used the power feed on the carriage to take the last .025" off the diameter, to final size. That left a very nice finish, and no taper. We learn---we learn---


----------



## 10K Pete

Success!! You're now using the lathe as intended. You are about to graduate.

woohoo1woohoo1woohoo1

Pete


----------



## Brian Rupnow

So---Here we have it, finished except for trimming the ends to get rid of the countersinks, and a keyway for the flywheel. It fits into the "engine block" just like it's supposed to. That 1144 stress-proof steel is a wonderful material. After all the machining operations involved, I put the shorter end of the crankshaft in the three jaw chuck on my lathe and put an indicator on the very far unsupported end, then rotated the chuck through 360 degrees. The total indicated runout was .003"!!! That is .0015" of "center shift". Almost unbelievable.  Not only did I manage to make a nice crankshaft, but I learned some good things about using my new lathe. I'm glad it's done. I have sweat bullets this week.---Brian


----------



## Swifty

Brian Rupnow said:


> This morning I turned the first main crankshaft journal, and discovered a dirty little secret. I have suspected all along that it would be almost impossible to set the topslide perfectly parallel to the ways. You can get it super close with a dial indicator, but I still didn't totally trust it. I confirmed that this morning by turning the crankshaft journal down over it's full 2" length using the topslide only, with the carriage locked, but I left the journal a bit  oversize. I then measured both ends with a micrometer, and sure enough, I was turning a very slight taper. Having established that, I locked the topslide and used the power feed on the carriage to take the last .025" off the diameter, to final size. That left a very nice finish, and no taper. We learn---we learn---



No ones ever too old to learn new tricks &#128515;

Paul.


----------



## Charles Lamont

Good job.

BTW, with work turned between centres, it is "normal" to leave the centre holes in.


----------



## Brian Rupnow

I've reached the point in this build where I need a bit more stable platform to set things on as I add them. I didn't want to invest any more time/work until I was sure that I was going to be able to make the crankshaft. Now that it is finished, I will go ahead and build the engine baseplate. This is not going to be an "oil in the base" engine. Oil will be administered from the open top, via squirt can. The milled "catch basin" in the baseplate will catch any oil drips and guide them out thru a drain hole in the front of the baseplate. I will probably put a perimeter gasket between the "engine block" and the baseplate to keep oil from seeping out onto the surface of the baseplate..


----------



## Brian Rupnow

And---we have a base. Not much to brag on here, because all the "features" are hidden inside the engine block. Still, it used up an entire afternoon, and it fits!!!


----------



## gus

Hi Brian.

You have given me the courage to machine crankshaft.
Looking for video on the first start and run.


----------



## Brian Rupnow

Hi Gus--glad you looked in. I hope everything is working out well on your engine.---Brian


----------



## gus

Brian Rupnow said:


> Hi Gus--glad you looked in. I hope everything is working out well on your engine.---Brian



Hi Brian,

Gus at 72 does get burnt out easily. Howell V-2 has too many small parts and all require my best concentration. No worry. I am now in the final assembly stage. 
To add to my woes, I cannot post fotos. Need the latest iPhoto download. My Apple NBook was just reformatted with the latest Apple d/loads. The New Apple 6S HandPhone takes time to get used to. With Christmas around the corner,I am getting lazy.


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## Brian Rupnow

This kind of puts me in mind of the old Doublemint gum jingle--"Double your pleasure, Double your fun!!!" I've spent a goodly portion of the past two days making cylinder heads. Each head has 5 drilled and counterbored holes, 11 tapped holes, one 1" counterbore, and two reamed and counterbored holes. I have not yet drilled the holes through that top surface with the 8 tapped holes in it to connect it to the valve cage holes. I will wait until the valve cages are made and installed, then drill thru the cylinder head and the valve cages at the same time.


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## canadianhorsepower

Brian Rupnow said:


> This kind of puts me in mind of the old Doublemint gum jingle--"Double your pleasure, Double your fun!!!"
> Brian
> Your DRO have the function to do that for you
> take  minute, OK afternoon and check the tutorial
> it does a lot more than giving you numbers:wall::wall:
> it give you ANSWERS ALSO Rof}Rof}Rof}


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## Brian Rupnow

Today I made a cam bushing. It's a bit more than a standard issue bushing though. It has a flange which bolts into a pocket in the side of the "engine -block" and an extended nose which fits into a reamed hole in the side of the engine block to keep everything aligned. It is made from bronze, and with this design I can remove the bushing and pull the camshaft with cams attached out through the front of the engine. The end of the extended nose also acts to position the camshaft longitudinally. The shaft in the picture is just a random length of 1/4" c.r.s. right now. The cams will be made seperately and attache with Loctite. (This works, and works very well. It is the method Malcolm Stride used on hid "Bobcat" engine.) The pocket in the side of the engine block is very precise, as it was cut on the mill. The perimeter of the cam bushing was shaped by hand, so it isn't a perfect gap all around. This is okay though---it all gets covered up by the gears and gear cover.


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## Brian Rupnow

We've got gears!!! They seem to mate and mesh properly, but I have to finish a couple of plain bushings, one for the crankshaft and one for the camshaft before I'm 100% certain. I only make about 3 or possibly 4 sets of gears each year, so I have written step by step instructions for myself in my "Gear book". It is simply a matter of coincidence, but these are the same gears that work on the Webster engine. The actual gear cutting is very simple if you have a rotary table and a set of gear cutters. The "work" is all in preparing the gear blanks to the correct size.


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## canadianhorsepower

Brian Rupnow said:


> We've got gears!!! They seem to mate and mesh properly, but I have to finish a couple of plain bushings, one for the crankshaft and one for the camshaft before I'm 100% certain. ]



Hi Brian 
Maybe you have these data sheets
I find them very useful 

cheers 

View attachment GEAR.xls


View attachment WORM AND GEAR BY DP CALCULATION SPREAD SHEET.xls


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## Brian Rupnow

Thanks Luc. I have all the gear cutting information.---The "if" part of the equation is my execution of the information.


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## Brian Rupnow

This falls under the heading of "creative fettling"!!! Although the gears turned out well, my center to center distance on the frame holes was out by about .015", too close together. I'm never quite sure how something like this happens, but it does. Sometimes the hole spacing is "right on", and sometimes they are a bit too far apart. "Right on" is great---nothing more required. If they are a bit too far apart, it's still okay, but the gears may be a bit noisy when the engine runs. When they are a bit too close---Well, still no cause for a major rework. I simply set the gears up in the lathe and turn .008" off the tip of the teeth. This still leaves lot's of tooth for engagement. Once the gears will turn in place (Albeit a bit stiffly and nasty) then I apply a bit of 400 grit carborundum paste to the gears, put a pulley on the crankshaft, and power it up with my 1/2 h.p. bale elevator motor. After a half hour run in, everything turns as smooth as silk.


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## Brian Rupnow

I thought of building a sub base from wood to raise the engine up enough to get clearance for the flywheel shroud---but I don't really care for woodwork all that much. I have come up with a design using 2" x 1/2" aluminum bars for the risers.


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## canadianhorsepower

Hi Brian
for some reason I was under the impression 
that It would have two carbs
Looking good Thm:


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## Brian Rupnow

Luc--I thought about two carbs. I still may go that route. It's just that with two carbs, you need a connecting link to synchronize them.---Brian


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## 10K Pete

That's the first pic I've seen of your engine, Brian. At first glance I thought
I was seeing an old VW engine!! Very cool.

Pete


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## Brian Rupnow

10k Pete---As you can see by my post count, I've been around here for a while. If you go back to the beginning of this thread, you can see how the current model "evolved" from my first ideas of designing a two cylinder opposed engine. I think this is my fifteenth or sixteenth engine build. I bought my first lathe and mill about six years ago, and manage approximately two engines a year.----Brian


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## 10K Pete

Oh I've followed your threads for a long time but for some reason had not
seen a pic of this one 'til now. Love your work.

Pete


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## Brian Rupnow

The time has come in this build to do a bit of finishing and a bit of verifying. I hadn't touched the inside of the cylinders, other than to ream them to size when I was originally machining them. Now that the crankshaft and camshaft are turning freely with gears attached it was time to check that the center of the connecting rod journals were lined up with the center of the cylinder bores. The way I finish my cast iron cylinders after reaming them is to run my three stone brake cylinder hone thru them under electric drill power, at a fairly low rpm, and everything covered with a bit of light oil. I run it back and forth for a rough count of 40 times, being sure to not let the jaws 'spring' out of either end while doing so. Then I turn a piece of round aluminum stock to .002" smaller in diameter than the cylinder bore, coat it with 600 grit carborundum paste, and put one end of the aluminum piece in the lathe and at low rpm slide the cylinder back and forth over it for about two minutes as it rotates.---I then turned one end of the homemade lap down to 0.375" diameter, and with the cylinder heads removed I slid the lap down the cylinder bore until the 3/8" end come out into the cylinder block. --In a perfect world, if everything was machined precisely, it would have fit perfectly into the gap between the crankshaft "throws".---In my world, I had to set the crankshaft up in the lathe and machine .025" off the outside edge of one of the "throws", and that did the trick quite nicely, as you can see in the picture. I think that now I will go ahead and make the pistons and con'rods.


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## Brian Rupnow

Good progress this afternoon on what are destined to become pistons.---


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## Brian Rupnow

The pistons finished up nicely. One of the issues I always have when making pistons, is how to put the wrist pin hole in and be perfectly sure it is at 90 degrees to the counterbored slot for the con-rod, and at perfect right angles to the central axis of the piston. I was given this tip some time ago, but never got to try it until yesterday.--The secret---set up in the rotary table chuck, on the mill bed, as shown here. Align the chuck jaws as shown, and put a "sacrificial" spacer between the side of the piston and the right hand jaw. My rotary table is "keyed" to the tee- slots in the top of my milling machine bed, so I am sure of it's position when it is bolted to the Tee slots. Make the slot which the con-rod fits into runs between you and the mill column (the Z axis).--Remember now, you have the rotary table locked in position---we are not going to rotate the attached chuck.  Once the slot is finished to size, undo the bolts which hold the rotary table to the tee slots and turn the rotary table with chuck attached (still gripping the piston) 90 degrees to the right so the centerline of the piston is parallel to the milling machine bed. Use a square to make sure the rotary table is setting 90 degrees to the milling machine bed and bolt it down to the tee slots again. Use your center finding device (whatever it may be) to find the centerline of the piston, zero your tool on the exposed end of the piston skirt, and move the table in the right to left (X-travel) to position the chuck directly above the position you want the wrist pin hole to be. Now you have the chuck jaws positioned so that you can run the drill down between them from the top with no interference, and you can drill (and ream) right on through the far side of the piston into the sacrificial aluminum spacer. This ensures that the wrist pin hole will be "square and true" to all the other surfaces.  If you are following this thread, please say Hi and let me know you are interested. I am about to embark on a pair of connecting rods.---Brian


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## Cogsy

I'm following along and enjoying Brian. Your builds are always chock full of helpful insights and your engines are awesome. I'm really curious as to what this one will sound like and I'm guessing it won't be long now til I find out.


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## Brian Rupnow

Guys--Thank you all so much for saying Hi!!! I think it's time to go to bed now. Before supper I KNOW that I laid out and cut out and drilled the inside radius holes in two connecting rods. I KNOW that I sat one down while I milled out the profile on the other one. I eat supper, and came back down to my shop. I wanted to take a picture of the two stages of con-rod profiling. The damned thing that I hadn't started to profile is GONE. I put away all my tools.--I cleaned up all the mess. I've walked out to the bandsaw and looked four times. I'm hoping that if I can get a good nights sleep, that whatever snuck in and stole my friggin' connecting rod will sneak in again and put it back!!!---Brian


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## pickleford75

Those little gremlins that steal our parts and tools sure are a pain!
anybody know of any good spray to get rid of them??? :wall:


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## barnesrickw

Magnet on a stick before you sweep..  Unless they are non magnetic, then they are just gone.


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## Brian Rupnow

Went to bed and thought for a while. Then I remembered I has set the second one up on a ventilating rad to dry a coating of layout dye.


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## Roboguy

It's so frustrating when you loose a part or tool you literally just had in your hand. Seems to happen on a regular basis to me! 

The engine is looking fantastic Brian.


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## Brian Rupnow

Roboguy said:


> It's so frustrating when you loose a part or tool you literally just had in your hand. Seems to happen on a regular basis to me!
> 
> The engine is looking fantastic Brian.


Yes--same problem no matter which side of the planet you live on!!!


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## Brian Rupnow

We've got sparkplugs!! We've got sparkplug wires and boots!! And we've made a good start on connecting rods and caps. I have one more con-rod cap to make, and then I can start profiling the sides of the con-rod and put in the big end bores.  There is a lot of work in these connecting rods.


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## Brian Rupnow

I'm very pleased with the way these connecting rods turned out. They are a full 3/8" thick at the big end boss, the rest of the rod is faced .033" on each side, to clear the sides of the crankshaft journal support arms and to fit into the 5/16" slot in the pistons. Also attached you will see the simple jig I came up with to machine them that way.


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## Brian Rupnow

Now, this is just kool, with a capital K.


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## Brian Rupnow

There are three classifications of assembly fit.   Tight, Real tight, and "Oh my Gawd!!" tight. I'm sure that this fits into the third category. The good news is that everything fits, and goes round and round and up and down with no interferences. While I had the cylinders off, I  lapped the pistons into the cylinders with 600 grit paste and a long "handle" purpose made for this job. I'm not sure this step is really necessary, but it knocks down any high spots on the pistons and gives a very nice sliding fit.--The pistons will slide slowly down a cylinder stood on end, but stop if I put my thumb over the bottom end of the cylinder to stop air coming out.--and this is dry, without any oil or piston rings. That big ugly collar on the camshaft is just that--a big ugly collar, to keep the camshaft and gear from sliding out of the block.--an added benefit is that the collar is the same o.d. as the maximum outer diameters of the cams will be, and the crankshaft clears it. Big sigh of relief. If there are going to be any major crashes, this is the point at which they show up, and all seems to be clear.


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## Brian Rupnow

So, here we have the engine mocked up into position, with the "Finger chopping flywheel from Hell" setting in place on the crankshaft. The cooling air provided by the vanes on the flywheel will blow directly onto the cylinders and heads. The metal "shroud" around the flywheel is stationary, and does not rotate. It will be bolted to the base. If I feel exceptionally wimpy when I go to actually run this thing, I may put a metal mesh between the flywheel and the engine, but Hey---Think of all the guys out there who are running airplane propellers on their engines with no guarding of any kind on them!! I can't really do much more today, as I need to buy material tomorrow to make the base risers with.


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## Brian Rupnow

A few years ago (10 or 12) when I built my last hot-rod, I come into possession of a radio speaker grill from some old car. It was an aftermarket kind of thing, but the pattern and shape of the openings in the metal cover was so beautiful that I decided I would keep it, in case I ever wanted a piece of "safety grill" for an application like this. I have just finished a thorough search of all my cupboards, and I can't find it anywhere. I will have another look tomorrow, because it would be perfect to cover the near side of the flywheel/fan shroud.


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## Brian Rupnow

The risers for the base are finished and installed. Now I can spin the flywheel and watch everything go round and round. Tomorrow I hope to complete the flywheel guard.


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## Brian Rupnow

I was afraid that my brazing skills might have left me. It's been about 30 years since I did any serious brazing. I went down to the welding supply shop this morning and bought a stick of 3/32" flux coated brazing rod. What do you know---I can still braze as good as I could in 1985!!! This is going to make my fingers a lot happier when I run this engine. I haven't made the mounting brackets yet, nor the guarding on the far side of the flywheel/fan, but I like this.


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## hussien95

Very cool work from a big master
:bow::bow::bow::bow::bow:


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## Brian Rupnow

Thanks Hussien---It looks like we are going to get a bunch of your fellow countrymen here in Canada in the very near future. I'll say Hi for you.---Brian


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## hussien95

Thank you brian.
Damn for terrorist who resolve Us.
I follow up most of your designs and I hope that i can make engine one day.


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## Brian Rupnow

The fan shroud/guard is finished, painted, and installed. I think it adds to the overall engine, and there is definitely a much greater safety factor now.  I like that satin finish black paint for jobs like this. It doesn't show up every small imperfection in the painted metal, but it does really make the brass and aluminum "pop" by contrast.---Brian


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## Brian Rupnow

We are well on our way to a brass gearcase.


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## Brian Rupnow

The gearcase is finished except for polishing. With the heads on and sparkplugs in place, I can see that the plug boot sets quite close to the base. I don't know if this is going to give me a problem or not. I won't really know until I actually run the engine if the plug wires are going to short out to the base. If they do, there is lots of "free space" under each cylinder to machine the base away, although that's not something I really want to do.


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## gus

Gear case looks good and expensive.

Its Christmas Eve here and hot and humid and rainy.

Merry Christmas!!!!


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## Brian Rupnow

Today I finished the rocker arm support brackets. As you can see, I have layout dye on the base--I figure it is much easier to cut away some material  to prevent the danger of ignition sparks arcing to the base at this stage of the game instead of waiting until later when all the parts are added. I am rapidly getting down to the "fiddly bits" of this build. Building an engine like this is a lot like eating an elephant.--If you look at the overall scope of how many parts there are, it's pretty daunting. If you just settle in and eat one bite at a time, it gets done eventually. Hope you all have a Merry Christmas and a Happy New Year. I have to go help grandma now, to get the house ready for an onslaught of children and grandchildren coming tomorrow.---Brian


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## Longboy

Brass is class. Looks nice dominating the front of the frame.


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## Brian Rupnow

A check of my mill tooling shows that the best cutter I have to put a relief in the base below the sparkplugs is a 5/8" ball nosed endmill.  Barring unforeseen difficulties, it should yield a result like this.


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## Brian Rupnow

Well--that worked out very well!!! The ball nosed endmill got the job done nicely, and now I have lots of clearance around the sparkplugs!!


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## Brian Rupnow

I am at the stage of this build now where I need something on the front of the engine which I can grip in my hand to turn the engine over with. I also need a receiver hub for the starter spud which I use in my variable speed drill to start the engine with. I used a similar set-up on my dual opposed piston engine and was satisfied with the way it turned out, so I will use the same set-up here.


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## Brian Rupnow

Today I machined the ignition cam, and installed it and the ignition points. I also made up a knurled handwheel to let me turn the engine over by hand. This knurled handwheel also has the center configured to take the "starter spud" which fits into my variable speed drill for starting the engine. I have not yet trimmed the crankshaft to length. After it is trimmed and the countersunk ends cut off, the end of the crankshaft will be more or less flush with the face of the handwheel.


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## ZebDog

hi Brian
I been reading your build on this engine from the stat great work
looking forward to the day she fires up for the first time

Steve


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## Brian Rupnow

If you are ever talking to anyone about model engines, and the subject of "Rocker arms" should come up in the same conversation as the words "easy" or " Nothing to it." I sincerely urge you to smack them up side of the head, and say "Brian told me to do that!!!!" Damn, there's a lot of work in four rocker arms!!!!


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## Brian Rupnow

The four valve lifter guides are made from 01 drill rod, then heated cherry red and quenched in a cup of oil. They are Loctited into holes in the block. I don't like to even think about press fitting things like this, because if you don't have a heat treat oven to reheat and "draw them back" a little in hardness, they are quite brittle and will shatter like glass. (Don't ask me how I know.) I had to make five of these to get four.--On the very first one I made, I turned the outer diameter .005" under .375. Surprisingly, my new lathe is just as happy to turn things undersized as my old one was!!! Now I have to go and shovel my front steps and walk, as we have our first real snowfall of the year.


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## Charles Lamont

You don't need anything sophisticated for a temper accurate enough for our work. You can use a small flame and go by the colour, or, for parts like your tappet guides, putting them in a domestic oven at 200C (~400F) will make them a good deal tougher without loosing hardness.


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## Brian Rupnow

You have to look really hard to see this, but the valve lifters are finished and installed in their guides. they also are made from O1 steel, flame hardened and quenched. I have shown them extended far beyond where they would normally set. When the cams are installed, they will ride right up against the cam lobes and very little will show above the outer lip of the valve lifter guides. These lifters have a counterbored pocket in the outer ends, which the push-rods for the valves will set into.


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## Brian Rupnow

It's hard to believe, but I'm starting to run out of things to make on this engine. I was going to make the valve cages tomorrow, but the company where I buy my valve springs won't be open until Monday, and I don't want to make the cages until I am absolutely sure of the inside diameter of the valve springs I will be using. Same goes for the valve keeper plates. I still have to make cams, but that's a whole different story. I was never able to get the original Jaguar engine using the cams designed by Malcolm Stride to work right without blowing vapour back thru the carburetor intake. I don't really think there was a problem with his design nor with my fabrication. Several people who built his Bobcat, which was a two cylinder version of the Jaguar didn't experience the same vapour problem. I am pretty sure that his cam design was for a high revving engine with considerable overlap in the valve train, and I am looking for a slower more industrial style cam , so I'm kind of saving the cams for the "last thing". I can probably build the valves tomorrow, and start thinking about intake manifold runners and exhaust pipes.


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## Brian Rupnow

Today was valve making day. Not a terribly difficult job, but time consuming. I do not turn my valves between centers. I hold the parent rod in my 3 jaw lathe chuck, and turn the maximum diameter (in this case .312") to size first. Then I turn down 1/3 of the stem length to within about +.002 to +.004 from finished size. Doing it this way minimizes the deflection that I would get if I tried to turn the full length down to .125". The brass piece in the picture is a remnant from a gear that was left over from another job. I drilled and reamed a 0.125" hole thru the center of it before I started turning the valves. After the entire valve stem length was turned to just a bit oversize, I then used 220 grit emery cloth to bring it down to final size. Of course, this means many stops to try the brass piece on to see when it will slide nicely over the valve stem. This "sanding" procedure brings the stem down to exact size, and removes 90% of the machining marks on the stem. I machined the stems with my lathe topslide flipped around to the rear side of the lathe and set at 45 degrees and locked--This way, when the stem was finished I could unlock the topslide and use it to advance the tool to put the 45 degree bevel on the face of the valve. I left about 3" of the parent metal attached to the lathe, as this will give me a "handle" to hold when I lap the valves into the valve seats with 400, then 600 grit lapping paste. After that is finished, I will cut the "handle" portion off and be left with only the valve.


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## Brian Rupnow

-I am not overly impressed with the finish on the 45 degree face, but that is because my new lathe doesn't turn as fast at it's top speed as my old lathe did. (Without getting into the work of changing the v-belt drive from low range into high range.) I'm not sure it really matters, as the machining marks on the face are annular grooves and will probably come out after the lapping process. I do have a high speed grinder which I can mount on the toolpost, which would give me a perfect face with no tool marks at all, but the grinder is air powered and kind of a pain to hook up.


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## Brian Rupnow

This week I hope to make my four cams, using the Cam-Calc software provided by the Model Engine News folks. This is the method which uses a rotary table and a vertical milling machine. It is not difficult-----just very time consuming. The i.d. of the cam is 1/4", the o.d. of the sleeve is 0.315", and the lift of the cam is 0.067".  The total length of the four cams mounted end to end is less than 1.6", and if I make a one piece cam and allow three 0.100" spaces for my 3/32" parting off tool, it is still less than 2" total length. The cams get Loctited to a piece of plain 1/4" cold rolled steel to make up the cam shaft. The cams themselves are made from 01 steel and flame hardened. That outer sleeve diameter of .315" is equal to the  "base radius" of the cam itself. I am going to try and cut one cam 2" long, with a reamed bore of 1/4" full length, then use my parting off tool to turn the round areas to 0.315", while leaving the actual cam portion unmachined. Then I will use my 3/32" parting off tool to cut the one piece cam into four individual pieces which will be hardened, then arranged rotationally and Loctited to the shaft. If this works, it will save me the work involved in cutting four individual cams.


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## Brian Rupnow

As much as I would like to take credit for the original design of the cam, and explain the science and reasoning behind it, I can't. This design is originated by Malcolm Stride of the U.K. and used on his "Bobcat" twin and "Jaguar" single cylinder engines. I have put considerable time and energy into studying all of the factors which go into cam design, and I have sufficient knowledge to design a cam from scratch, using formula's developed by Stride and by Mason. However, this is one of the instances where I don't fully understand the science involved. I just know that it works, because many people built the twin cylinder "Bobcat" using this cam and posted videos of the engine running. I did build the single cylinder "Jaguar" version, again using this exact cam, and it ran, although I never was able to resolve the issue of it occasionally expelling jets of vapour thru the carburetor intake. Since I only began machining things about 6 years ago, I believe the occasional jets of what appeared to be exhaust vapour thru the carburetor intake may have been more of a testament to my questionable machining ability than anything to do with the cam design.---Brian


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## Brian Rupnow

Todays offering to the Machining Gods are four valve cages. I purchased the compression spring in the picture this morning, as I wanted to have it before I machined the cages. I have a valve inserted into one of the cages (The valve still has the "handle" attached to it). These cages have to be Loctited into the cylinder head, and although it should be a light press fit, you really can't press them too much or they deform. I have ordered some Loctite 620 retaining compound, as it is supposedly much more heat resistant than the 638 I have always used. I will not put the valve "seat" into the valve cages until after they are Loctited into place.


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## Brian Rupnow

I am struggling to make my way through the cam timing, as originally determined by Malcolm Stride. This is exactly the timing diagram and valve profile as published for the Bobcat and Jaguar engines. I plan on using it for this new engine I am building. This is not easy to get my head around. I think I have 95% understanding after pouring through books published by Malcolm stride and L.C. Mason


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## Brian Rupnow

Now let me see if I can get my head around this. The piston is moving from top dead center to bottom dead center on the power stroke, with both valves closed. 40 degrees before bottom dead center, the exhaust cam which is leading begins to open the exhaust valve. Since there is a 1:2 relationship between crankshaft revolution and camshaft revolution, that translates to 20 degrees of camshaft rotation.
As the piston reaches bottom dead center and begins to travel up on the exhaust stroke, the exhaust valve stays open during the full upwards travel of the piston which represents 180 degrees of crankshaft rotation, or 90 degrees of camshaft rotation. Then as the piston reaches top dead center on the exhaust stroke, the exhaust valve stays open for 20 degrees of crankshaft rotation (10 degrees of camshaft rotation) during the intake stroke before it fully closes. This adds up to a total of 240 degrees of crankshaft rotation, or 120 degrees of camshaft rotation.
SoLets back up a little bit to where the piston is coming up to top dead center on the exhaust stroke with the exhaust valve wide open. 15 degrees of crankshaft rotation (7.5 degrees of camshaft rotation) before the piston reaches top dead center, the intake valve begins to open. It stays open thru the full intake stroke of the piston (180 degrees of crankshaft rotation, 90 degrees of camshaft rotation, and then as the piston reaches bottom dead center on the intake stroke and begins to move upward on the compression stroke, the intake valve stays open for an additional 45 degrees of crankshaft rotation, (22.5 degrees of camshaft rotation.)
This adds up to a total of 240 degrees of crankshaft rotation, (120 degrees of camshaft revolution).
So---we see that the exhaust cam and the intake cam must in this case have the same profile, since they must both be active an equal number of degrees of rotation. We also see that there is a total of 35 degrees of overlap at top dead center where both intake and exhaust valves are open at the same time.---this is typical of a mid-range power/speed  engine. Hi speed/ hi-performance engines can have a greater overlap, while slower running engines must have a smaller overlap.
Now, there is a marvelous calculation used to position the intake and exhaust cams rotationally in respect to one and other. I have read this calculation enough times to make my head explode, and will repeat it here:
Take the total of the valve open periods, divide by 2, subtract the total valve overlap and divide the result by 2
Sothe total of the valve open periods is 480 degrees of crankshaft rotation, divided by 2= 240 degrees.
240 degrees -35 degrees of overlap=205 degrees. Then 205 divided by 2=102.5 degrees of rotational separation between the intake and exhaust cam lobes.
This information was gleaned from a number of sources, but primarily from information found in Model Four Cycle Gasoline Engines by C.L. Mason and in Miniature Internal Combustion Engines by Malcolm stride.


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## Brian Rupnow

Here is another novel way of determining the cam lobe separation.  I haven't seen it done this way before, but it works. This method presupposes that you know the lead and lag of the valves in relationship to the crankshaft so you can divide them by two and enter them as values for the camshaft, then by bisecting the curve and matching it to the centerline of the cam lobe it establishes what the cam lobe separation should be.


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## Charles Lamont

Looks to me as though you have mastered it. Had you not been intending to make all the cams at one go, I would have suggested a slightly fatter exhaust cam with an earlier opening would be more normal. It will probably make little difference in practice, as you probably won't be putting it on a dynamometer.


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## ozzie46

Brian; Thank you, thank you, thank you!!!Thm:Thm:Thm: I have been trying to get my head around this for quite a while and now you make it seem so simple.

 Great build by the way. I may not say much in your posts but I do follow along on every one of them. I always seem to pick up some great nugget of information in each of them.

Ron


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## Brian Rupnow

Not a lot of machining today. Spent too much time sussing out the mystery of cams and their rotational orientation to one an other. However, thanks to other forum members helping me, I think I have it mostly right now. I did prepare four cam "blanks" from 01 steel, turned to size and reamed to 1/4" to fit on the cam shaft. I gave up on my idea of milling all the cams at once because it was going to get a bit too complicated, so they will be milled using Cam Calc figures, and milling one at a time (Oh, my aching arthritic shoulder!!!). Oh well, I don't have to do them all in one day.


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## petertha

Brian Rupnow said:


> Here is another novel way of determining the cam lobe separation. I haven't seen it done this way before, but it works.


 
I like your 'cad' layout method. You can actually compute the resultant lobe separation & overlap numbers in a spreadsheet like I did (post #3) knowing intake/exhaust open/close inputs. But faking a cam layout visualization in Excel is a pita.
http://www.homemodelenginemachinist.com/showthread.php?t=21808

Where I see added value in your method is multi-cylinder engine design. I think your cam sketch can be copy transposed for remaining cylinders, adjust for their crankshaft layout/firing order & now the whole camshaft can be fully defined as all lobes are angularly related to one another or any arbitrary reference if you wanted to mill/grind a cam shaft.


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## Brian Rupnow

A rather crummy picture---but cam #1 is cut and setting in place. It still needs a bit of polishing and has to be hardened yet, but it is the first one and it fits. I don't do this cam making business often enough. After cutting this first one, I see that I COULD HAVE CUT ALL THE CAMS AT ONCE!!!----DAMN!!!  Oh well, I'll remember now.


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## Brian Rupnow

It's been an interesting and somewhat frustrating day. I made three cams. I actually started four cams, but had a brain fart on the second one and started feeding the endmill down instead of up---didn't realize it until about the fifteenth cut. I am not really happy with the finish on these cams. I moved the milling table back and forth in the Y axis to make these cams, and I'm wondering if that was a mistake. It seems to me that when I built other cams using this vertical mill method that I got a much better finish on them, but I may have been moving the table in the X axis when I made them.---I simply don't remember. The cams set right up on top of everything and are very visible, so I can't even hide them away deep in the bowels of the engine.  EDIT--EDIT---I just went back and looked at my build thread for the original Malcolm Stride inspired "Canadian cub" and the cams were marvelously smooth, and they were machined by moving the table in the X axis.


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## Brian Rupnow

-My mistake---I meant to say that I moved the table away from me and towards me while cutting the cams, which as I understand it is the Y axis. I have removed the "Z" from my previous post and replaced it with a "Y". The Z axis is the spindle movement.


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## Brian Rupnow

Today I remade the cam as one long piece, all cam shaped. I moved the table of the mill right to left which is the X axis, and the finish was much, much better than the cams I made yesterday milling in the Y axis. I still have "miles to go before I sleep" on this, as the next step is to set it up in the lathe and turn down the areas which must be round and not cam shaped, and then part off 4 individual pieces. I'm still not sure if I'm "out of the woods" on this cam yet. I will post pictures if and when I get to something picture worthy.


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## Brian Rupnow

Every so often, the good guys do win!!! Had a very breath holding, tongue biting morning, but everything parted off okay, and the cams all fit where they are supposed to. Now, if I can just flame harden them without melting them (they are pretty darned small) and get them Loctited to the shaft in the correct rotational aspect, we're away to the races!!!


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## Charles Lamont

Excellent work. So it is just the right time to pour a thimbleful of cold water over it! Brian, your tappets are too small. I am not absolutely sure, but I think you will find the cam riding on the edge of the tappet as it comes up the flank radius towards the nose radius. I am assuming a flat-faced tappet, if curved it's different. This line joining the flank and nose radii of the cam marks the maximum velocity of the valve, and the maximum dispacement of the contact point (line) from the centreline. The tappet should be of such a diameter that it covers this line across the full face width of the cam.


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## Brian Rupnow

Charles--The tappets are exactly the same diameter  as the tappets used on the Jaguar and Bobcat engine. The bottom of the tappet is flat, and the tappet is 1/4" diameter, while the cam itself is 0.157" wide. The cam has radiused flanks.The flame hardening and quench went well (I didn't melt nor distort the cams), and they all fit back onto the camshaft after being cleaned up a bit and degreased. I will Loctite the cam closest to the timing gears into place later today.


.


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## Charles Lamont

I have checked that geometry out with CAD (easier than doing the trigonometry) and it is "OK" by a fine hair's breadth. The contact line comes to within less that 0.003" from the edge of the tappet face, so it does not cover the full width of the cam, narrowing to less than 1/16 wide. For contact across the full width of the cam throughout, you would need a theoretical tappet diameter of  0.290". However, firstly this is the point at which the opening tappet starts to decelerate, so the forces are low, and secondly, it looks as though about half a thou. of total wear would produce a full contact width. Hope I have not caused undue alarm.


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## Brian Rupnow

You didn't!!


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## Brian Rupnow

This has absolutely nothing to do with the current thread-----But---I went and seen the new Star Wars movie this afternoon.--My God---It was fabulous!!!--I loved the first 3 Star Wars movies, hated the second three Star Wars movies, and didn't really know what to expect with this newest release. Disney has bought the franchise from George Lucas, and they really did it right this time. This movie has everything that old sci-Fi buffs like myself love.--Okay, Okay---Back to more mundane things like engine building now.---Brian


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## Brian Rupnow

What to build, what to build next??? I can't do anymore with the valve train stuff until my bottle of #620 Loctite comes in to assemble the valve cages into the cylinder heads.  Probably a good a place as any is the exhaust stacks. In the original model, I had faked in a pair of intake manifolds in the position of the exhaust stacks. I like the vertical stacks as shown here, and I like the angle cut ends on them, although that is purely a cosmetic thing.


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## Brian Rupnow

I spent the afternoon making two exhaust stack flanges. There is a bit more to these flanges than meets the eye-----They are machined thinner on one side where two of the #4 shcs go thru, to make clearance for the pushrods which pass directly over top of them. Work this size is right on the ragged edge of "Too small" as far as I'm concerned.----and---My digital camera is definitely on the way out.


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## Brian Rupnow

The engine now has a set of exhaust stacks. They look kind of huge, and almost overpower the rest of the engine, but I'll have to make a judgement on that after I get the induction system built and installed. I can always cut the length of them down to look better if I want to later. --On the subject of induction systems--I THINK I seen mention of someone who sells pre-bent sections of hollow brass tubing in 45 degree or 90 degree bends, but I don't remember where.--If somebody knows, please let me know.


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## Cogsy

Looking mighty fine but I think the stacks need their angle cuts.


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## Brian Rupnow

Cogsy said:


> Looking mighty fine but I think the stacks need their angle cuts.


I agree Cogsy--I won't cut them though until I get the intake system sorted out and installed, because the intake system is going to visually have some effect on just how long the stacks should be.


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## Brian Rupnow

It is time now to give some serious consideration to the induction system. On my original model, I had one tube with  a 90 degree bend only, the other tube had a 90 degree bend as well as an offset. Since I am using the two cylinder ports which are closest together as intake ports, this means that the offset is minimal. If I set the intake up like this, I can make both intake tubes identical, and make the central carburetor block where the intake tubes come together with an offset incorporated into it.--I'm not sure about this yet.--I may find that the brass tube is easy enough to bend that I will use my original idea.


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## Brian Rupnow

Today I made some progress on the intake system. I didn't use brass tubing. I picked up a length of copper-nickel automotive brake-line, which bends very easily without flattening or kinking, and it seems to be exactly what I needed. This is the main part of the intake roughed together but not soldered yet. I decided to go with my original idea for the brass centerpiece and bend an offset in the right-hand side bent tube.


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## Brian Rupnow

I've been a busy guy the last couple of days. The intake system is all soldered together and polished.--I really hate polishing things like this. There are just so many sharp corners and angles to catch on the spinning buffing wheel, rip it out of your hands, and fling it around the room.--You immediately have to stop and count your fingers when this happens!!! Fortunately, I still have all of mine, albeit gouged up in a couple of places. I borrowed the carburetor from the Canadian Cub, as I can always build another carburetor after this engine is up and running to replace it. I chickened out on the enormous exhaust stacks. They looked too "cartoonish" for me.---Like something out of a 1960's "Trucking" magazine. I took Jason's advice and reworked them into "stacks with mufflers". My old digital camera did die, just like I thought it was going to. I had to go down street yesterday and buy a new one, and judging by the pictures shown here, it works pretty good. I'm waiting now for the Loctite 620 to come in so I can finish up the valve cages into the heads. We are getting close to the finish line now, and it's getting exciting. So far I have followed the 3D model quite closely. I may rethink the position of the gas tank, but I'm not sure yet.


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## Brian Rupnow

This morning we have pushrods and valve spring "keepers" (shown on the valves setting in front of the engine). The pushrods are made about 1/2" longer than their finished length will be. I will trim them to the correct length after I get the valves, springs, and keepers and cages installed in the cylinder heads.


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## Brian Rupnow

I picked up a used 12 volt dual output ignition coil today from a local motorcycle shop for $10.00. We tried it out at the dealers, but the spark seemed very very "wimpy". We tried out about four different used coils and this was the only one we had any success with. It was giving a spark from both ignition wires, but it was pretty feeble. I don't really know how well the battery was charged at the dealers when we tried out the coil.----So---I brought it home to try it out on my 12 volt battery, and wouldn't you know it, my 12 volt battery was dead!!! So, now my battery is on the charger, and all I can do is wait for it to charge.There are two high tension cables coming out of the case, and two small gauge wires, one red with a white stripe and one solid orange. I am assuming the red wire with white stripe is the positive feed, and the orange is the ground to complete the primary circuit. I don't have any prior experience with dual output coils, but I'm sure the sparks from the high tension leads, when it's ran off a fully charged battery should be big fat blue ones, not anemic yellow ones. If the coil is no good, I'm only out $10 but I'm hoping that after the battery is fully charged I get better performance from the coil.


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## 10K Pete

I think there needs to be a chunk of iron connecting the ends of the iron that
the coil is wrapped around for the field to form correctly. I suspect that the original
mounting did that. ????

Pete


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## Brian Rupnow

I went out this morning and borrowed the 12 volt battery from my lawn tractor. With everything hooked up, I am back to getting a pair of very anemic sparks from the high tension leads of the dual output coil when I momentarily connect, then disconnect the low tension leads. I don't really buy this bit about the condenser giving a stronger spark, but I have been wrong before. I have to go out in about 10 minutes to quote a job, so I will pick up a new points and condenser while I am out, as I will eventually use them anyways, and that will give me a condenser to wire into this "try-out" circuit. I'm not sure about the mild steel mounting bracket having any effect on the magnetic field either, but I will make one up to see if it makes a difference. I am basing my negatives on the fact that when you hook up a 12 volt automotive coil as I have this dual output coil, it will give a fat blue arc half an inch long, without benefit of condenser or mild steel bracketry.


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## canadianhorsepower

> I don't really buy this bit about the condenser giving a stronger spark, but I have been wrong before.



the condenser will not give you a stronger spark, it's going to save your point cause it's cutting the magnetic field and because it oppose itself to a current change it will give you a longer spark then your point would.



> I'm not sure about the mild steel mounting bracket having any effect on the magnetic field either, but I will make one up to see if it makes a difference.



the bracket has nothing to do with it, you already have the piece of metal you need for your core.



> I am basing my negatives on the fact that when you hook up a 12 volt automotive coil as I have this dual output coil,



remember Brian this coil CAN give you a spark at both lead at he same time but it won't on your engine cause one cylinder will be lean and the other one fat. to duplicate that and see the real output of your coil ground one HT wire when doing your test.

Cheers


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## Brian Rupnow

I just wired a condenser into the circuit, and as I expected, it really didn't make any difference to the spark from the high tension leads. I was taught that a condenser is in the circuit for the following reason, and has nothing to do with enhancing the ignition spark. When the current flow to the primary windings of the coil is interrupted by the points opening, the collapsing magnetic field induces a current flow in the secondary windings to produce the spark. The fact that the magnetic field is collapsing also induces current flow in the primary windings, and this current flow has to reach ground---However, the points have just started to open, breaking the circuit and creating the induced current in both sets of windings. The current induced in the primary windings will jump across the newly opened points to reach ground. This arcing will soon break down the contact surface of the points and "burn the points out". However, if there is a condenser in the circuit, this induced current in the primary windings will flow into the condenser and be slowly bled off to ground instead of arcing across the points contact surface.---At any rate, I am getting consistent anemic yellow arcs from the high tension leads. I would like to know more about this mild steel bracket that supposedly enhances the operation of the coil. I suppose that since I have to mount the coil somehow, I can incorporate a mild steel bracket into the mounting to see if this is a real or imagined benefit.


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## Brian Rupnow

All four valve cages have been liberally coated with 620 Loctite and pressed into the cylinder heads. "Press fit" is kind of a nominal term. You can't make it a hard press fit, as the cages will distort from the pressing. On the other hand, you don't want them to "fall" into the holes in the head either. Every time I build one of these engines, the fits end up a little different. I had two cages that couldn't be pressed in by "hand" and two that fit so poorly I went around the perimeter with a prick punch to upset the metal and increase the diameter a bit. This 620 Loctite retaining compound is a new one for me. It has a much higher temperature rating than the #638 that I have always used before. You will notice that I haven't put any chamfer on the seat portion of the cages yet. I will wait 24 hours for everything to set up good, then drill the passages that go through the cylinder heads and the sides of the valve cages, and then I will use my "George Britnell seat turning tool" by hand to put in a 45 degree x .015" chamfer on the area that the valves seal against.


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## Brian Rupnow

I'm down to my very last piece of 1" brass tubing that I salvaged from a pole-lamp about 5 years ago. That lamp has certainly made a lot of gas tanks over the years!!! Unfortunately, I gave away my Steve Bedair type ball turner, because I never used it, so the gas tank ends are going to have a slightly different shape than the tank in the 3D cad model.


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## Brian Rupnow

If we go with the assumption that this engine may run someday, at least we now have a place to put the fuel. I haven't put in the outlet nor the support bracket yet. I will wait until I have the engine all back together before I finalize that part of the gas tank.


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## Brian Rupnow

Voila'!!! We have valves cut to length, lapped and installed. The keeper pins setting in the top of those valve keepers are only 0.039" diameter. I will have to check each valve individually to make sure they have enough travel between fully open and fully closed. The total "lift" on my cam shaft is 0.067", and I must have at least that much travel + 10% total movement possible on my valves.


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## Brian Rupnow

We've got rings on both pistons-----


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## nfk

Hi Brian,
After reading your issues with the ignition coils, i've started experimenting with a few i got at home.
I had a strong spark once i figured out the wiring.
Your coil is a genuine Yamaha part (4h7-61).
Those coils attach directly to the bike frame, needing battery ground on the metal bar.

After watching a few wiring diagrams, i think you would need to wire the battery negative terminal on the metal bar and contact points should go on the red cable. 
The orange should be for engine stop or RPM measurements.

I'm not sure if the coil you have is for a TDI (not CDI) ignition system. If that's the case, it won't work without an actual TDI ignition controller and supplementary coil.
TDI systems require a special stator coil to work.
Look at the coil with black tape on the stator below.
http://mla-s2-p.mlstatic.com/estato...pton-110cc--15129-MLA20096844517_052014-F.jpg

Hope this helps

Norberto


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## Brian Rupnow

I've had to back-track a little bit and add a piece between the intake manifold and the carburetor (the red part) to move the carburetor a bit to make more room for the gas tank. Although it looked okay on the original model, there were just too many things fighting for space. Also, I wasn't really comfortable with the carburetor air intake being right tight beside the gas cap on the tank. I have seen those carbs backfire and spit out a flame, and positioned right tight to the vented gas cap would not be a good thing.


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## gus

Waiting for your engine to----------Vroom-----------Vroooooo0000M!!!


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## Brian Rupnow

And now you know what I've been doing the last few days!!! I swear to God, there is more work in that gas tank than there was in the first two engines I built 6 years ago!! And yes, there is a gap between the gas tank and the black painted flywheel shroud. It's only about 1/16", but it is a gap.--Which is light years better than an interference. The only mechanical thing I have left to make is the red offset bracket to move the carburetor over a bit as shown in the previous solid model.


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## Brian Rupnow

I just shocked the living Hell out of myself messing around with this used $10 dual output coil I got the other day. There is more going on here than I know. If it will give me a kick like that, it should certainly fire a sparkplug. I think that a more sophisticated test rig is called for  now, other than touching two wires together. Incidentally, the positive feed goes to the red wire with the white stripe. The orange wire goes to the points, then to ground. I'm not 100% sure that the steel laminated bar through the middle has to be grounded or not, but I am going to assume "probably". After I make the last part tomorrow to modify the intake manifold, I will make up a test rig with two real sparkplugs in it and let you know the results. I will also make up a steel "horseshoe" that attaches to both ends of the laminated steel bar to see if that has any effect on the strength of the spark.


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## Brian Rupnow

Well, there it is--mechanically finished!!! The pushrods for the rocker arms aren't cut to finished length yet, because I still have to "phase the camshaft" and Loctite the individual cams to the shaft. The gas tank is finished, and all the gaskets are in place. The carburetor clears everything very well with the 45 degree adapter I added between the carburetor and the intake manifold. I think this is the prettiest engine I've built yet. The next big "sorting out" will be the dual output coil and the camshaft phasing. We are getting very close to trying to start this thing.--I won't say a "running engine"---that would be tempting fate!!!


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## Brian Rupnow

I built a steel "horseshoe" shaped bracket from 3/8" steel to mount the coil on, and using my spark gap tester and a spare sparkplug I have hooked everything up and seem to be getting good results from my used $10 dual output motorcycle coil. I didn't mention it in the video, but I was not using a condenser in this test. I did try with a condenser in the circuit after I made the video, and I think it improves the quality of the spark, but it is rather hard to tell.
[ame]https://www.youtube.com/watch?v=vhy0MA_8bKM&feature=youtu.be[/ame]


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## Cogsy

Brian - I'm not sure how the gaps compare between your tester and the spark plug, but I noticed that around the 1:29 - 1:35 mark of your video the tester appeared to miss a couple of sparks and only the plug 'fired'. If the gaps are substantially different this may be the cause. I've never been overly fussed about plug gaps in model engines but I'm guessing you'll have to make sure yours are close to the same for each plug.

Waiting eagerly for the noisy video!


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## Brian Rupnow

My next move is going to be Loctiting the cam segments to the camshaft, and this has me really nervous.---So nervous that I decided I had to make a 3D cad model of all the affected parts, then after all the appropriate mates were added drag the crankshaft around through 360 degrees a couple of times and watch the cam rotate at half the speed of the crankshaft in the opposite direction and see where the tangency points of the cam flank intersected centerline of the valve lifter. I have simplified my cad model by leaving out the pushrod and rocker arm, but the geometry still applies. This took me a goodly portion of the morning, and after doing it I discovered somebody had given me bad information about separation of the cam lobes!!!----WHAT!!!---COULDN'T BE!!!  I decided to take a break and take my lovely wife for a drive down to Orangeville, where my daughter and her husband may buy a house.---I came home and decided to check everything on my cad layout one more time---and discovered I had made a mistake!!  The information I was given about cam lobe separation was good.--So---Tomorrow is Loctite time!!


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## Brian Rupnow

The individual cams are now Loctited to the shaft with #638 Loctite. The shaft was degreased with laquer thinners and sanded longitudinally with 160 grit garnet paper to give some "tooth" for the Loctite to grip. The inside bore of the individual cam segments were degreased with laquer thinners and a cotton swab to get any traces of oil out of the inside. The first cam slid into place was an exhaust cam, and the high point of the cam was held horizontal with the V-notched plate you see setting on the bed of the mill. the rotary table was set at the "0" mark. After a wait of 20 minutes to let the Loctite set up, the rotary table was rotated 102.5 degrees and the next cam, which was an intake cam was slid into place and again positioned with the v-notched plate. Since the third cam in was another intake valve, the rotary table was not moved---the third cam was slid on and positioned 180 degrees out of phase with the second cam in by using the v-notched stick from the opposite side. The rotary table was then indexed to the 180 degree mark and the final cam section slid into place. as you can see in the picture, it's a bit of a gooey mess right now.--That's okay though, because I don't want to wipe any Loctite away and accidently disturb the position of the cams. After a 24 hour set-up time, I will remove the shaft from the rotary table and scrape away any excess Loctite--(it cleans up quite easily with sandpaper).


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## Brian Rupnow

The dual output motorcycle coil is mounted to the back side of the engine. I have one angle bracket to finish and mount for the on/off switch. I removed the large diameter ignition wires from the coil (they simply pull straight out of the sockets.) The ignition wires for the very small Rimfire sparkplugs are only 0.100" in diameter, but I have discovered a nifty trick to use them with automotive ignition coils, or any coil that originally came set up for 0.284" (7 mm) diameter wires. I take a piece of hardwood dowel, turn the outside diameter to 0.284", and drill the center out with a 1/8" drill. Push the small diameter wire through the dowel with some bare wire exposed at the end that fits into the coil, and coat the last 1/2" of the other end where it goes into the wooden dowel with a bit of epoxy.  Wood is a good insulator, and it works really well.


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## Brian Rupnow

I woke up this morning with the horrible feeling that I may have screwed up the cam segment positions for the second cylinder. My intent with this engine is that the cylinders fire on alternate cycles. When piston #1 is at top dead center on compression, ready to fire, piston #2 should be at top dead center on exhaust stroke. So, it seemed logical that the second two cam sections should set at exactly 180 degrees to the first two cam segments and that's the way I Loctited them in position. Later in the day, when the Loctite had set up good, I put the camshaft back into the engine and turned it by hand to watch it's influence on the various valve lifters. As the cam rotated into position to begin lifting the intake valve on cylinder one, the cam right beside it which operates the intake valve on cylinder #2 also began to lift the intake valve on cylinder #2.   I thought that seemed a bit unusual, but tucked the thought away into my belfry with the rest of the bats, and went on with other parts of the engine. This morning, as I lay awake in bed planning my day, the thought occurred---My theory of having the cams for the second cylinder at 180 degrees to the first cylinder was absolutely correct.---IF the cylinders had both been on the same side of the crankshaft. However, the cylinders are 180 degrees apart on opposite sides of the crankshaft.---so--today I will heat up the last two cam segments and rotate them 180 degrees.---I'm tellin' ya---This camshaft business is not for wimps or old ladies. I love learning new stuff, but this cam business has me stretched quite a bit beyond my normal limits!!!


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## cwelkie

So close Brian - looking very good!
I disagree with this though:

_"I love learning new stuff, but this cam business has me stretched quite a bit beyond my normal limits!!!"
_
... you figured it out in the end.  You continue to do (and share) things many of us wait for guys like you to do before we even try.  Thanks for that.
Charlie


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## Brian Rupnow

cwelkie said:


> So close Brian - looking very good!
> I disagree with this though:
> 
> _"I love learning new stuff, but this cam business has me stretched quite a bit beyond my normal limits!!!"
> _
> ... you figured it out in the end.  You continue to do (and share) things many of us wait for guys like you to do before we even try.  Thanks for that.
> Charlie


Charlie---I don't mind figuring stuff out---I just wish I would figure it out right the FIRST time around.---Brian


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## Brian Rupnow

Today we got on/off switch, indicator light, and plug in for wires to battery installed, and sparkplug wires in place.---and changed the position of the two cams that operate the valves on the cylinder closest to the flywheel. The switches aren't wired yet, that will be tomorrows job. At first I was going to wire the indicator light in series with the coil, then I decided that if I did that the light would blink off every time the ignition points opened.---So--I will wire it parallel to the ignition circuit. I will reinstall the cam tomorrow and start buttoning everything up.


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## Brian Rupnow

I'll tell ya right now!!--Setting valve timing ain't for sissies!!! I've been at this since I got up this morning, but some of the time was spent cutting the pushrods to length and adjusting the valve lash, some of it was spent machining knurled brass "handles" for the end of the valve lash adjusting screws, and a LOT of the time was spent setting valve timing, then , resetting it, and resetting once again. Things tend to move when you tighten them up. I may not have it absolutely dead nuts right, but it's mighty close!!!


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## Brian Rupnow

After a long and somewhat tedious day, I have everything back together and buttoned up and seem to have reasonably good compression. This is a rather subjective thing at this point, because with the new Viton rings in place the engine is pretty stiff. I can feel considerable difference now  with the valves set and the pushrods in place. Tomorrow I will tackle the wiring, and if all goes well, I may try and start the engine.


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## Johno1958

Although I'm not a machinists boot lace, I've been following along and I really like your build.
Best of luck.
I can't wait to hear it sing.

Cheers
John


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## Brian Rupnow

Thanks Johno---I'm always glad to hear from the Aussies.---Brian


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## bmac2

Im rooting for ya. Chair pulled up, Coffees on, and fingers crossed.


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## Brian Rupnow

Wiring is finished, and it's time to start the engine--I'm working on it right now.  Have had a few exciting "pops and farts" but no joy yet. The heavy break-in oil that I had in the cylinders is fouling the sparkplugs before it has a chance to actually start and blow all the oil out of the cylinders. I just took it outside and with the sparkplugs out injected gasoline into both cylinders, swished it around good, 2 or 3 times repeatedly, then blew the cylinders out with my air hose at 100 psi.  The engine is setting out in my main garage now, reeking of gasoline. I will let it dry out for an hour and then have another try. That was the only thing i didn't like about this design, was the sparkplugs laying almost at the bottom side of the cylinder. If the engine floods, or you have any residual oil in there, it fouls the plugs and then you can't clear them until you remove them from the engine and dry them off.


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## Brian Rupnow

Okay--First round of "attempts to start" is over. Even after flushing the break-in oil out of the cylinders, it's not firing. I have double checked the sequence of the valve timing and the ignition timing, and they are right on spec. The sparkplugs are giving a nice crisp spark (At least when they are laying out on the cylinder head). Those exhaust stacks are positioned perfectly to do the old "Pucker up and blow your guts out"  trick. If neither valve is up on the cam, and you can't blow down the stack while holding the exhaust valve open under finger pressure, that shows that your intake valve isn't leaking. If you can't blow down the stack while the intake is closed and the exhaust is open, that shows that your combustion chamber and head gasket isn't leaking. if you can't suck air thru the stack while holding the intake open and the exhaust is closed, that indicates that the exhaust valve isn't leaking.---Very crude and rudimentary tests, yes, but they do show up "gross leakage". Of course, nothing seals perfectly on a brand new unrun engine. It's all a matter of "degree" of leakage. I'm not ready to tear anything down yet. Next trick will be to put a pulley on it and drive it at about 500 RPM with my half horse electric motor, while tweaking the fuel mixture with the ignition "on" to see if I can get it to start firing.


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## canadianhorsepower

Brian,
to my opinion the intake runner are way to long for 
such a small AND low RPM engine.
GOOD LUCK


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## Brian Rupnow

Things are looking up!! with the engine being driven by my electric motor, I have tweaked fuel mixture and timing to the point where the engine is firing consistently on one cylinder, and inconsistently on the other. It is very cold and fairly dark out in the main garage and I've had enough for today. I think that now I have to play about with the ignition timing. The secret to this driving an engine with a motor is to get the engine firing, even if it's not running under it's own power. Every time it fires, it helps seat the valves a little more, until the combustion chamber becomes air-tight. Of course this won't fix badly ground valves, but if the valves are very "close" to being a good seal, this just adds the finishing touches.---more tomorrow.


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## cwelkie

canadianhorsepower said:


> Brian,
> to my opinion the intake runner are way to long for
> such a small AND low RPM engine.
> GOOD LUCK



Hi Luc - if that were the case my Aeronca E118 shouldn't run at all ... and its carb is under the engine!  <grin>

Sounds like you're on to it Brian!  Tomorrow should be THE DAY.
Charlie


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## canadianhorsepower

cwelkie said:


> Hi Luc - if that were the case my Aeronca E118 shouldn't run at all ...  <grin>.
> Charlie



it would be nice to see a video or a picture if they exist 
( of it running of course)

cheers


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## Cogsy

I'm all the way onto the edge of my seat Brian. I'll remain here until tomorrow. Good luck.


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## Brian Rupnow

Last evening while trying to start the engine out in my main garage, I noticed that it was occasionally sending out a puff of smoke between the right side cylinder head and the cylinder. I was away all day today on a design job, and when I got home tonight I squirted some liquid dish detergent on the joint and turned the engine over with my variable speed drill. Sure enough---bubbles, bubbles everywhere. Will now pull the head off and have a look.


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## Brian Rupnow

And yes, boys and girls---it happens just that fast!!! I have work to do yet, but this truly is the first run. I was surprised when it started right up and ran after I changed the head gasket on one side, and fortunately my camera was setting within reach. YAHOO--YAHHOO---YAHOO---more later after some serious tuning.---Brian
[ame]https://www.youtube.com/watch?v=Jhgla-362jo&feature=youtu.be[/ame]


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## cwelkie

... and there you go!
Congratulations on a successful run.  Everything from here on out are just niceties.
Sounds great Brian!
Charlie


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## Cogsy

Awesome! Sounds like it's running great and you haven't even started tweaking it yet. You make it all look so easy...


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## Brian Rupnow

Some quick observations--The right hand cylinder with the new head gasket seems to be the dominant cylinder right now. I think the valves could still use a bit of attention in the left hand cylinder. It is firing and getting hot, but I can tell when turning the engine over by hand that the compression isn't as strong in the left side cylinder, and there don't appear to be any leaks in the left side cylinder head gasket. The "vanes" on the flywheel are blowing a good draft of air directly across the cylinders. The engine doesn't want to idle down to a slow "tick over" right now, and I think that is due to the one weak cylinder. The gas tank looks great where I have it, but I just ran the engine out of gas, and I'm afraid to fill the tank because of the hot cylinders directly below the tank. When trying to start it with my variable speed drill, the right hand cylinder was firing like crazy, but simply didn't have enough power to run the engine by itself. When the left hand cylinder kicked in, you could really hear and feel the difference.  The heavy brass gear case seems to soak up all of the noise made by the timing gears. This is very exciting, as it is my first twin cylinder engine.---And I don't see any puffs of vapour coming back thru the carburetor like my clone of Malcolm Stride's Bobcat or Jaguar engine.


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## Cogsy

In the first video it sounds like it runs fairly slow already but will surely improve as it is run in. Remember it will sound twice as quick as you think it's running because of the two cylinders - you're only used to hearing one fire so 500 RPM will sound like a thousand.


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## Swifty

Well done Brian, although I've been quiet during your build, I've been following along with every post. It's a great feeling when an engine runs for the first time.

Paul.


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## ShopShoe

Congratulations.

I've been waiting for this one to fire.

--ShopShoe


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## barnesrickw

Success is the best answer to doubt.


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## Johno1958

Congratulations Brian.
That sounds sweet.

John


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## Brian Rupnow

Thanks guys--I can't really feel a difference in the exhaust gas temperatures between the right and left hand exhaust stacks, but I can't really feel any compression on that left hand cylinder when rotating the crankshaft by hand. I'm about to dive into that left hand cylinder and do a quick rework on the valves and maybe replace the headgasket. One of my goals when I built this engine was to have an open crankcase so the inner workings would be visible. This works great in theory, but in practice all you really see is a grey blur in there. I think I will make a polished brass top for the engine that sets in place with a locating register and 4 small super magnets Loctited into the underside which mate with 4 steel slugs set into the top of the angle crankcase. That way it will be easy to remove to oil the inner works with a squirt can, but will give a more "finished look to the overall engine.


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## burkLane

Brian Rupnow said:


> One of my goals when I built this engine was to have an open crankcase so the inner workings would be visible. This works great in theory, but in practice all you really see is a grey blur in there. That way it will be easy to remove to oil the inner works with a squirt can, but will give a more "finished look to the overall engine.


 
Hi Brian,
Great project , I have followed your work for years now.
I was thinking a while back  a 0.5 " clear acrylic cover would be a nice touch to your design! Figured I would toss that idea out and praise your work at same time!
Enjoying your threads and all the eye candy pictures you post  "I love drawing"
Lane


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## Brian Rupnow

burkLane said:


> Hi Brian,
> Great project , I have followed your work for years now.
> I was thinking a while back  a 0.5 " clear acrylic cover would be a nice touch to your design! Figured I would toss that idea out and praise your work at same time!
> Enjoying your threads and all the eye candy pictures you post  "I love drawing"
> Lane


I considered that.--But--clear acrylic isn't anywhere as pretty as polished brass and there is enough oil flying around in there that it would only be "see through" for seconds after starting the engine.---Brian


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## Brian Rupnow

"Awesome" is a word that is often overused!--However, after a quick relapping of the valves on the left hand cylinder and a new head gasket for that side too, there aren't many other words to do this engine justice!!! My God---It is "awesome"!!! I will post a better lighted and better planned video tomorrow. I can now feel lots of compression on both cylinders when turning it over by hand.


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## Charles Lamont

Brian Rupnow said:


> That way it will be easy to remove to oil the inner works with a squirt can, but will give a more "finished look to the overall engine.


Careful now, or next thing you know you might find yourself building an engine with a proper enclosed crankcase and splash lubrication.


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## Brian Rupnow

Charles, I have done that, and I wasn't happy with the result. When you can no longer see into the crankcase, you really have no idea of what the oil in there is doing. The amount of oil is so very small that it's hard to check with a dipstick. Either you don't have enough oil and bearings burn out as a consequence, or you end up like Jason, who built basically this same engine (although his was far more streamlined than mine), and found out that the rotating crankshaft picks up oil and slings it straight into the bore of the right hand cylinder causing it to burn oil and foul the plug because of so much oil in the cylinder barrel. My engines are not ran for hours and hours at a time. I much prefer being able to readily access the crankcase and give a few squirts with my trusty squirt oilcan. There is a drainhole that is open in the bottom of my crankcase to let excess oil out!! This way I know how much oil is reaching the bearings and can give it a squirt of oil before running it.---brian


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## Brian Rupnow

As I promised, here is a better lighted and better planned video. I do a bit more "voice over" on this video to explain some things about the engine. You get to see the start up procedure, the low speed, and the higher speed it is capable of. Thank you again to everyone on the forums who have followed my build threads and offered advice and information. This engine is a complete success, and the results are everything I had hoped for.---Brian Rupnow
[ame]https://www.youtube.com/watch?v=whXt2ZTvw1c&feature=youtu.be[/ame]


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## james_III

Congratulations, that sounds just like it should and clearly this thing wants to run, start was so easy


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## gbritnell

Extremely well done Brian. I think of all the engines you have designed and built this one runs the nicest. 
gbritnell


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## Brian Rupnow

Thank you George and James. Someone has asked that I post a few still shots of the finished engines, so here it is.---Brian.


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## RonGinger

Nice job Brian. Let me be the first to ask, So what do you do next? I can not imagine not having a near  daily read of your latest adventures. How about something more scale, like an old VW 4 cylinder?


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## Brian Rupnow

Thanks Ron--I have the notion that having successfully built singles, twins, flatheads, and overhead valve engines that my next build is going to be a two stroke. I have seen Jan Ridders 2-stroke plans, and they don't really appeal to me that much. I have seen a number of people on the forums who have built them but are unable to make them run without modifying them in some way, or else never get them to run at all. I need to find a proven design for a 2 stroke that doesn't exceed my current machining abilities.---Brian


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## Brian Rupnow

Here is a nifty little trick for "old school" engine builders like myself, who still use a 12 volt battery to power the ignition on their engines. Rather than have a big ball of wire wound up with the engine when it is not in use, or two separate leads with alligator clips, I purchased a microphone connector plug at Sayall Electronics. Half of it mounts into a bracket on the engine, and half of it can be attached to the wire leads which run to the battery. The connections are solder type and can be easily connected with a small soldering gun. The lowest number of connector pins available are three, but that's not a big problem---Just use two, one for the hot wire and one for ground. The two plugs only fit together in one orientation so there is no danger of plugging it in wrong.


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## Cogsy

Runs like a dream Brian. Definitely would like to build my own one day.


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## Brian Rupnow

I have just went in and reloaded the final Youtube video, using a different format to get a crisper, cleaner video with no fuzziness. It is much clearer now.---Brian


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## Roboguy

Just watched the new video. The engine looks and sounds wonderful. Congratulations Brian and thanks for sharing!


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## ozzie46

Great job as always Brian. The engine sounds super.

Waiting for the next installment of "Brian's Small Engine Shop".


  Ron


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## Brian Rupnow

Got my laser tach out this morning and took a few readings. The lowest idle rpm without "faltering" seems to be about 1175 rpm. this surprises me a bit because it SOUNDS slower than that. The highest rpm seems to top out at about 4000 rpm, but remember, I am running with almost zero advance on my ignition timing, and it is fixed. My timing doesn't advance as the throttle is advanced.


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## Brian Rupnow

I went up to Princess Auto this morning and bought a package of 10 "supermagnets" for $6.00 ---These things are incredibly strong in their attraction to any ferrous metal and to each other. I used a .344" diameter endmill to put two shallow pockets into the top of the angles which make up the framework of the engine, and two pockets into the underside of the polished brass top plate, then used J.B. Weld to anchor the magnets in place. I certainly hope I have the magnets in the correct way so they attract and not repel!!! This should take any rattling and clattering away when the lid is setting in place on the engine. I might need three men and a bulldog to get it off to oil the engine with my squirt-can.--- J.B. Weld takes a terribly long time to "set up", at least 24 hours, so I won't know until then if I have the magnets in the right way or not.


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## canadianhorsepower

Brian Rupnow said:


> e. I might need three men and a bulldog to get it off to oil the engine with my squirt-can.--- J.B. Weld takes a terribly long time to "set up", at least 24 hours, so I won't know until then if I have the magnets in the right way or not.



You will need a Bull Dog  to pull it up  Rof}Rof}
to make your life easier slide it to one side then pull Magnet don't have any shear power


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## Brian Rupnow

Good thought Luc---But, as you can see in the picture, the lid sets down into the top of the engine and can't be slid to one side. However, if I need a bulldog I'll give my ex wife a call----


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## Brian Rupnow

I sneaked downstairs this morning and filed/sanded the excess j.b. weld away and tried the brass top plate for fit. It snaps into place very solidly--and is easy enough to remove that I won't need the bulldog!!!.---Brian


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## Brian Rupnow

This is it!!! The polished brass top plate with the embedded magnets fits snugly in place, doesn't rattle when the engine is running, and yes, I can lift it up to remove it with my fingers. This will be my last post about this engine unless I am answering a question in response to someone. It's been a fun ride!!!---Brian


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## Brian Rupnow

I have been asked on one of the forums I post on about the temperature of the engine, and how effective the fan blades on the outside of the flywheel are at cooling the engine. I had a devil of a time hunting down my remote sensing laser pyrometer, but I found it hidden in the bottom of a drawer. (It's not something you use all that often.) The engine will run exactly 10 minutes at a fast idle on one tank of naptha (Coleman fuel). Temperatures were taken during the last minute of the run. The cylinders run at 150 to 170 degrees F. The base of the exhaust stacks measure at about 185 degrees F. The ambient air temperature in the room is about 65 F---(I had my office door open to keep from gassing myself.) I would say that the cooling vanes on the flywheel are very effective with readings like that.I checked my tachometer against the readout on my lathe, and the tachometer agrees within 3 rpm of the readout on the lathe, so I guess that pretty well confirms that the lowest idle speed of the engine is around 1200 rpm, although it certainly sounds slower than that.


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## AussieTom

Congratulations Brian,

I have been quietly watching this build the entire time, i'm very impressed with the finished engine. Beautiful work!


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## Longboy

Beautiful easy runner!Thm: Enjoyed the video. What kind of "mileage" or run time does your fuel tank provide for your twin?  ------Dave


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## Brian Rupnow

Longboy said:


> Beautiful easy runner!Thm: Enjoyed the video. What kind of "mileage" or run time does your fuel tank provide for your twin?  ------Dave


It runs 10 to 12 minutes on the amount of fuel in the tank.


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## modelmotor

Hallo Brian,

I am very sorry for my very belated reply on yours about my Boll 8,2 cc model glow engine.You wrote about the fact that your engine was ready just a couple of weeks.
I have read and looked after the photos from your multi cilinder model engine and i must say Brian that the real Craftmanship you are well Skilled person i also saw that earlier when i made the thread on about one of my other homemade engines.
Congratulations with these perfect results your engine looks great you may be very proud of it.

                                                      many greetings from modelmotor-Gerard-The Neherlands-Europe.

All my compliments for you Brian!!!


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## Brian Rupnow

I am reviving this old thread because I recently had a gentleman from USA want to purchase a set of plans for it. This involved opening about 70 Solidworks CAD drawings and saving them as .pdf files so they can be opened and printed without any specialized software. If anyone is interested in purchasing a set of these plans, I sell the complete set for $25 Canadian funds. Contact me at [email protected] if you are interested in purchasing a set of the plans.--Brian Rupnow


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## pushrod_38-

Brian Rupnow said:


> I woke up this morning, thinking about an opposed twin i.c. engine. something along the layout of Jason's flat twin Boxter, only a bit cruder perhaps, with an open crankcase and exposed camshafts and crankshaft. I really like the knife and fork style con rod layout, and the fact that it lets the opposed cylinders set in line with each other. I haven't really sorted this through in my head yet, but this would probably mean two camshafts, one above the crank to run the right hand cylinder and one below the crank to run the left hand cylinder.-----Or perhaps both camshafts above the crankshaft, offset to each side. A single centrally located carburetor with long intake runners to each side---maybe. I have to think on this a while.---It feels interesting----Brian



Have a look at my book 'Designing and Building a miniature Aero Engine' (Crowood Press). There are pages to look at and an E version if you want a better look. These are air cooled, open rockers with push rods working from a cam cluster for each cylinder. I use three currently to fly my model aircraft.


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## Victor J

Hello Brian, Sorry if I am jumping in here but you were unsure if Glow engines were only 2 strokes in a very early date in this old thread. Well I am about half way through a10.5cc Vee 8 four stroke manufacture of a glow powered model aircraft engine. This engine was designed and built around 1995 in the UK. If you look up 'Whittle Vee 8' on you tube you can see one running.I hope this info may be of use to you for future projects.By the way I reside in the east of Scotland UK


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