# V-TWIN---MAYBE V-4



## Brian Rupnow (Jun 15, 2022)

I have been so impressed by RReid's build of a v-twin engine on "Model Engine Maker" forum, that I've just had to start modeling my own version. I will use the same cylinder, piston, and cylinder heads (although one of the heads has to be machined "opposite hand") as my 7/8" bore horizontal engine. It is not terribly difficult to design a V-twin engine. However, I'm thinkin' Lincoln,--what if? What if two V twin "stand alone" engines were completely finished then mounted on a common baseplate. Then, with the correct rotational aspect between the two engine crankshafts (using a Lovejoy coupling), wouldn't that make a reasonable v4 engine? I think the second engine would have to be a complete 180 degrees out of phase with the first engine to make this work right, but I'm not totally sure yet. I'm not going to build any engines this summer, but I do love to design.---Brian


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## stevehuckss396 (Jun 15, 2022)

Go 3 cylinder radial. Not many of those around


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## Brian Rupnow (Jun 15, 2022)

Okay---That's enough silliness for today. The timing gears are just hanging in space for now, not really positioned accurately.


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## lee webster (Jun 15, 2022)

Pardon my ignorance on this subject, but back in the late 60s my dad bought a new Ford Transit minibus. It had a V4 1750cc engine, with two crankshafts. The second crankshaft was a balance shaft. Do all V4s need one?
As a side note, we did 150,000 miles in that Transit in 3 years, same clutch and the heads were never taken off.


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## Brian Rupnow (Jun 15, 2022)

Hell, yes!!!--We can do this. All four valves have lifters. I have one idler gear on backwards but that will be changed. Tomorrow I will figure out how to support the idler gears and work on ignition.


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## Brian Rupnow (Jun 15, 2022)

Lee Webster--I can't answer your question, because I really don't know. I've never built a v-style engine before.---Brian


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## Ghosty (Jun 15, 2022)

Brian,
Why not put the cam between the cylinders, I know yours would be different, but less machining. Twin I built, 35cc
Cheers
Andrew


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## Brian Rupnow (Jun 15, 2022)

Ghosty--I didn't put a common camshaft in the center, because I didn't think of it. Your engine looks very nice. Does it run well?


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## Brian Rupnow (Jun 15, 2022)

With all the gears turned to have the hubs facing in the correct direction, I went ahead and designed a gear guard. I'm not sure of the final shape---It currently looks a bit too much like Mickey Mouse ears. I'll worry about that one tomorrow. The endplates for the crankcase are 1/2" thick, so that lets me use two 3/8" diameter shoulder bolts to support the idler gears.


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## animal12 (Jun 15, 2022)

You may want to look at some Harley engine pictures , their engineers fit a lot of parts in the lower ends of their engines .
animal


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## Jasonb (Jun 16, 2022)

As your cylinder/head layout can be traced back to Malcom Stride's Bobcat engine he was also ahead of you in other option s for these common parts. This was the beginnings of the NE45 -V6, I would think he was going to run the single cam down the middle at the top of the block, only needs one set of gears and a lot less friction. It has a Schillings type crankshaft


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## Badhippie (Jun 16, 2022)

Brian 
Are you thinking about just basically connecting the crankshafts up to each other?? Am I reading that correct. I ask because I am pretty sure this will not work do to the slight difference between engines such as RPM and getting the firing order on the cranks just right. If you look at pulling tractors or anything else with multi. Engines they all are connected through gear boxes and such. 
Tom


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## Brian Rupnow (Jun 16, 2022)

My thought was to couple the crankshafts together end to end. This would give the same result as one long crankshaft. The crankshafts would have to be "timed" with each other rotationally in order to have the firing order work correctly.


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## Brian Rupnow (Jun 16, 2022)

With two cylinders, each of which must be timed more or less independently of each other, the simplest way for me to do this is with two sets of ignition points. That doesn't really trouble me, and I've found that by mounting the ignition cams to the camshafts, I can bolt a 1/4" thick flatbar across the back of the crankcase endplate to support them. My original thoughts on this engine was that I would run it with an open crankcase similar to what RReid done on his engine, but I see now that I can run it with a closed crankshaft with splash lubrication for the con rods.


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## Brian Rupnow (Jun 16, 2022)

I've never had a lot of luck putting tight bends into small tubing without kinking it. So---I'm going to make the intake manifold out of a piece of 1/2" aluminum plate. The carb is my old tried and true Traxxas 4033, same as I've used on my other engines.


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## Brian Rupnow (Jun 16, 2022)

And of course, being an internal combustion engine, it needs a fuel tank. Fuel tanks are generally pretty boring, but I can fancy them up a bit with a real swoopy support bracket.


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## Badhippie (Jun 16, 2022)

Brian 
After giving this design some thought. I think you may want to think about connecting your camshafts together. I think that this may be a easier way to get your ignition timing to work. I just don’t think you are going to be able to just connect the cranks together. I believe if you do it that way one engine will always try driving the other engine. And that will happen back and fourth. But if you also connect the cams together then I think your design has a very good chance becoming a great design. There is one other component that may allow you to use both engines independently of each other and that is by using a viscous coupling that would allow the engines to have normal variance’s between the two and maybe prevent a dominant engine. I truly look forward to see this engine development 
Tom


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## Peter Twissell (Jun 17, 2022)

There is no problem with coupling two engines together as Brian is proposing.
A V4, V6, V8 etc. Is no different to a row of V twins.
I have been working on a land speed record bike which had two parallel twin engines (supercharged and running on methanol and nitromethane) coupled together with gears.
They need to be timed to one another to minimise stress on the gears at maximum power.
Model engines which are to be run under no load will be fine the way Brian wants to do it.


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## Badhippie (Jun 17, 2022)

That’s kind of what I was saying that it had to go through a gear box first. Brian was originally talking about just using a love joy coupler to couple the engines together. If anything I would not use a lovejoy. I would use a omega coupling at the very least.


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## Peter Twissell (Jun 17, 2022)

It's not a gearbox, just a row of three gears of the same size, adjusted for minimum backlash. The gears are from Aerial Square fours (which are effectively two parallel twins in one case).
Brian's idea with effectively two independent engines and no load will be fine with the Lovejoy coupling.
Either that or rigidly fixed cranks, which would give the option of a single set of timing gears.


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## Brian Rupnow (Jun 17, 2022)

I went to bed last night, and as I lay there thinking about this engine, I realized that I had neglected to put a flywheel on it. Okay, that lets me get rid of the Mickey Mouse ears gear guard and put two smaller gear guards on--The rest of the gears are covered by the flywheel. I like this much better.


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## lee webster (Jun 17, 2022)

I did wonder about the flywheel, but I felt it was so obvious I should keep quiet..........


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## ShopShoe (Jun 18, 2022)

Brian,

I like the way it looks with the flywheel too.

I definitely want to watch you build it: I'll be watching.

A V4 version would also be wonderful, but it would obviously take longer. Maybe that would be tiring for both of us........... (wink)

--ShopShoe


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## Brian Rupnow (Jun 21, 2022)

Ghosty--I've been thinking of why I didn't put the cam between the cylinders like you did. My cylinders are directly opposite each other, using knife and fork style connecting rods. That means that my valves and cams are directly opposite each other also. I need four separate cams to do this, layed out as I show them in my model. I couldn't squeeze all the cams onto one central camshaft.


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## Jasonb (Jun 21, 2022)

Should not be a problem, you would only need a camshaft about 1" long and just let the pushrods run at an angle. The rods would run straighter than say a Hoglet and cam shaft would be no longer.


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## Brian Rupnow (Jun 21, 2022)

Today I thought about pricing brass to use for my flywheel and gas tank. The one supplier I contacted in Barrie, wants $25 for a piece of 4" round brass 1" long (My flywheel). I then tried to find a piece of 1 3/4" round brass to use for a gas tank. Best price I could get was $40 for a piece 3 1/8" long. Not really complicated parts to make, but I like the color contrast. Okay, maybe I'll try something else.--I did a web search for cans of metallic spray paints that are a close match for brass. A spray can of "metallic brass finish" costs $10.00.  Hot rolled steel for the flywheel and  and thin wall steel tubing for the gas tank are so cheap that they almost give it away. In fact, I have some lying around in my materials bin. So---Use hot rolled steel that is essentially free (because I have it) and $10 for some spray paint, or $65 for material to make flywheel and gas tank. The only thing I gain by using brass is that I find it much easier to machine. Somehow it feels a bit like I'm cheating to make something from steel and then painting it to look like brass, but that's a heck of a big price differential.


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## animal12 (Jun 21, 2022)

Brian Rupnow said:


> Ghosty--I've been thinking of why I didn't put the cam between the cylinders like you did. My cylinders are directly opposite each other, using knife and fork style connecting rods. That means that my valves and cams are directly opposite each other also. I need four separate cams to do this, layed out as I show them in my model. I couldn't squeeze all the cams onto one central camshaft.


On the Harley 45 Flathead they had 4 cams under the cam cover to run the 2 sets of valves . Must have worked ok seeing as how they made that engine up until 1973 .
animal


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## Peter Twissell (Jun 22, 2022)

Brian Rupnow said:


> Ghosty--I've been thinking of why I didn't put the cam between the cylinders like you did. My cylinders are directly opposite each other, using knife and fork style connecting rods. That means that my valves and cams are directly opposite each other also. I need four separate cams to do this, layed out as I show them in my model. I couldn't squeeze all the cams onto one central camshaft.


Brian, if the tappets are at the same V angle as the cylinders, you only need two cams. One inlet for both cylinders and one exhaust.
I used this principal on my boxer twin.


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## Brian Rupnow (Jun 22, 2022)

Today I finished detail drawings of all the engine parts. There are 35 drawings including the overall general arrangement. I like the dual exposed camshafts.  It is probably a bit more work to do it this way than with a single center camshaft, but I like the "mechanical" look of it. The extra gears aren't as big an issue as you would think. I just cut my stock extra long when I cut the 24 dp. gears and then part off as many as I need. I've done a bit of preliminary pricing of material, but haven't done any machine work.


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## Brian Rupnow (Jun 23, 2022)

Some good views on the engine--


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## Brian Rupnow (Jun 23, 2022)

And a bit more--


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## Brian Rupnow (Jun 23, 2022)

And a bit more again--


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## Brian Rupnow (Jun 23, 2022)

And one final kick at the can, and that's all folks!!!


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## Badhippie (Jun 23, 2022)

Brian
Damn you have been a busy guy you even have a BOM made up. Very nice work can’t wait to see this start taking shape 
Tom


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## Brian Rupnow (Jun 23, 2022)

Badhippie--I love to take the credit, but actually the software does that for me. It's almost like magic.---Brian


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## Badhippie (Jun 23, 2022)

Brian 
You can go ahead and take the credit someone still has to input it all. I won’t tell anyone lol. 
can’t wait to see the results. 
Good Luck
       Tom


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## Brian Rupnow (Jun 23, 2022)

I had to break down and machine something today. I've read every book in the local library, downloaded everything that I would like to read on my tablet, and done all the household chores my good wife could think of. I actually caught myself reading a book about Zombies today, and decided "Oh boy--Better go machine something.----Zombies---Oh Lord!!!" So, first parts today---Camshaft supports.  I still have some finessing to do on them, and I won't drill the shaft holes until after the main crankcase and gears are made.--I've been caught out on this one before. Far wiser to let the gears determine where the hole for the shafts will be. I know where they go dimension wise, but anytime there is a possibility of stacked up tolerances, it is better to assemble the gears and center-punch thru the bore to get a true center distance.


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## Steamchick (Jun 24, 2022)

This is like starting a new detective novel. You can guess the plot, but the details will turn up some surprises, before reaching (usually) a happy ending that just makes you smile.
Keep up the good work Brian.
K2


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## stevehuckss396 (Jun 24, 2022)

Well that didn't take long.


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## Brian Rupnow (Jun 24, 2022)

Today I'm playing with gears. I have a full set of 24DP gear cutters, which seem to fit the size of engines I build very well. I also have a drawer full of random gears that have been recovered from abandoned projects. This little treasure chest of gears yielded two of the 30 tooth gears that I will need. I prepared a 1" diameter piece of  cold rolled steel so that I can cut two 20 tooth gears from it. I only need one, the second will go into my drawer of spare gears. I prepared a piece of 1 3/4" stress proof steel to become two 40 tooth gears. In a perfect world, I would have made the idler gears out of brass, because there is a theory out there that gears of dissimilar metals run quieter. However, since I have the two 30 tooth idler gears already, they are what will be used. Next step will be to set up my rotary table and milling machine to cut teeth on the gears.


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## Brian Rupnow (Jun 25, 2022)

After thinking about it for a bit, I decided to go with a brass flywheel. I could have used mild steel (which I already had) but decided it was worth $25 just to avoid all the bandsawing and shaping involved in making the piece from a  1" mild steel plate. I do love those radiused inside corners.


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## Brian Rupnow (Jun 26, 2022)

Today was crank-case day. I started with a piece of 4" diameter solid aluminum. My largest drill is one inch diameter, and the finished hole diameter is 3".--So, you know what I've been doing for a goodly part of the day---boring. and boring, and --boring. All of the inner features are finished now, so next thing will be milling the flats for the cylinders and camshaft supports to bolt to.


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## Gordon (Jun 26, 2022)

Your vow to not do any machining this summer did not last very long. Summer just started last week.


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## Brian Rupnow (Jun 26, 2022)

Gordon--You are absolutely right. A month ago I was so tired of machining things that I wanted to take the summer off and do other interesting things. Come to find out that at 75 years old, there just aren't that many other interesting things to do. I've read until my eyes are sore and I've used up all the good books that I wanted to read. Grandchildren are too grown up or live too far away to go and spend time at the beach. All my yard work is caught up, and I'm starting to drive my good wife crazy, looking for something to do.  ---Brian


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## Brian Rupnow (Jun 27, 2022)

Today I managed to crank out a pair of crankcase endplates. The 3/8" sealed ball bearings fit into a recess bored on the inside of each end plate. Lots and lots of other small holes, some tapped, some not.


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## Brian Rupnow (Jun 28, 2022)

Sometimes when I am machining parts, I'm making it up as I go along. I should have turned the two inch radius in these engine support brackets with them mounted on my lathes faceplate. However, that would have involved drilling and tapping hold down holes in my parts or my faceplates, so it was machined on my mill. My boring head will just reach a 4" diameter cut, and I already had the 3/4" holes designed more for "pretty" than anything, but at the last minute I drilled them undersize and reamed them to 0.750". That let me gang the two plates together and push in some boring tools with 3/4" shanks. I hogged out most of the material with my bandsaw, so the job went quite well on the mill, even though it required a wacky set-up. As you can see in the pictures, they turned out quite "spiffy". I was away part of the day, attending a graduation ceremony for my oldest (18 years) granddaughter, who surprised us all with graduating from high-school as an "Ontario scholar"--which means with an 80 percent or greater average grade. Way to go Hannah!!!


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## Brian Rupnow (Jun 29, 2022)

And now I have a place to mount my two sets of ignition points. I have one ratty old set of points that were damaged in the past. They work very well to just bolt in place and confirm that I have made the drawing correctly.


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## Brian Rupnow (Jun 29, 2022)

And that's it for today!! The support feet are attached to the crank-case. I have to trim the length of the bolts, but that can be tomorrows job.


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## Brian Rupnow (Jun 30, 2022)

At this point in the game, just as I am about to machine the cylinders, I have changed the design of the cylinders and cylinder heads. My original cylinders and cylinder heads were exact copies of the cylinder and heads that I used on the 7/8" bore horizontal. These cylinders were tapered at the top, and the heads were 1.6" diameter.  I have decided that due to the mass of the crank-case, the cylinders and heads had to appear larger. This didn't change anything internally---it's just that with the taper removed, the cylinders and heads "grow" to 1.9" diameter. I think this gives a much better overall "balance" to the engine.


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## Brian Rupnow (Jul 1, 2022)

Here we have the new cylinder which doesn't have tapered fins on it and the old style cylinder which does have tapered fins. Both cylinders are the same bore and same length, but the new style with untapered fins looks much more robust in comparison to the crankcase. I was going to make a second cylinder this afternoon, but I feel a fit of lazy coming on, so will make the second cylinder tomorrow. They are made from cast iron.


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## Brian Rupnow (Jul 2, 2022)

So, now we have two cylinders the same. Second cylinder went considerably faster than the first one. I started this one at 10:00 this morning and finished it at 12:30. I like making all of these large parts first.  Tomorrow I will get the tapped holes and clearance holes and the o-ring groove finished in the cylinders. I had some thoughts this morning about a cooling fan, and will probably spend some design time this afternoon to rig a cooling fan that is driven by an o-ring belt off the flywheel.


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## Brian Rupnow (Jul 2, 2022)

When you end up with the cooling fan and the carburetor both wanting to be in the same place, this is what you do. Looks wild and crazy, but I can't see any reason that it wouldn't work. I've got lots of things to do before I get to the point where I need to make this intake-carburetor-fan mash-up, so I've got a while to think about it.


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## Steamchick (Jul 3, 2022)

Hi Brian, this looks like you are sucking cold air over the intake mainfold, then blowing that past the engine, so the hot air will pre-heat the fuel tank and fuel. Is that a good plan?  Or could the fan go the opposite side to blow the heat away from the fuel tank? Or maybe re-mount the fuel tank so it gets cold air, not hot? Off to one side perhaps? Not in-line with the exhaust ports?
Just ideas...
K2


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## Brian Rupnow (Jul 3, 2022)

The intake manifold doesn't give off any heat. The air blowing over the cylinder fins will pick up some heat, but nowhere's near it's heat saturation point. If the fuel tank heats up, I would be surprised. There really isn't any other good place to put a cooling fan.


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## Brian Rupnow (Jul 3, 2022)

Spent the first half of today drilling and tapping 18 holes in the crankcase and sideplates to get everything bolted together. Probably the next thing will be putting threaded holes and clearance holes in the cylinders.


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## Steamchick (Jul 4, 2022)

Hi Brian, Thanks for post#54. I understand. - My only experience is with motorcycle air-cooled engines, where intake manifolds can get hot, and insulation is required to keep the heat from conducting to the Carburettor. So I had surmised that you wanted the fan there to help cool the intake manifold, by drawing air across it that then blew across the cylinders. 
How will the exhausts fit?
This is another intriguing build - Thanks for posting your work.
Cheers!
K2


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## Brian Rupnow (Jul 4, 2022)

Look at post #49---The exhaust are the short blue tubes coming straight out of each cylinder head.


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## Steamchick (Jul 4, 2022)

Thanks Brian. When I looked at post #52, I thought those were spark plugs, and the exhausts would have been opposite the inlets.
Now I understand...
K2


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## Brian Rupnow (Jul 4, 2022)

So, here we are with both cylinders drilled, tapped, grooved for o-ring head gasket seal, and bolted into place on the crankcase. Oh my, what nasty little buggers those socket head capscrews are that hold the cylinders in place. It would have been a lot simpler if I had cut the bottom cooling fin off each cylinder to give myself some more clearance. I didn't want to give up that cooling fin, so I shortened up one end of an Allen wrench and tightened them up, about 1/4 of a turn at a time. Ah well, it's progress.


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## stevehuckss396 (Jul 4, 2022)

If the hole pattern in the block and head match, just drill the hole through the cylinder. Use long screws to hold the head on that go all the way through the cylinder into the block. I have always liked the way that looks.


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## Brian Rupnow (Jul 4, 2022)

I've never done that, but it certainly would solve the clearance issue on the bolts.


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## stevehuckss396 (Jul 4, 2022)

It looks pretty cool too. Use fasteners that are un-threaded except where needed. Try it in CAD and see if you like the look.


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## Steamchick (Jul 5, 2022)

Hi Brian, Steve. (re: post #60). 
There are very good engineering reasons for long bolts holding engines together. (Simply put, Long springs keep the load, short ones vary the load: The long studs act as long springs holding everything together while temperatures change and expansion and contraction occur.). Especially when an engine has "long" Alloy components and steel bolts, sealed by "hard" gasketing. So "what looks good" is sound Engineering practice. 
But Brian's design is using O-rings, not "hard" gaskets, so the O-rings will have the compliance to compensate for "Joint movement". Additionally, with the same materials for block, bolt and cylinder head the expansion and contraction variation between bolt and parts is effectively zero. - Again, good Engineering here.
K2


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## Brian Rupnow (Jul 5, 2022)

I'm running out of "quick and easy" parts to build. Today I will attempt the swoopy looking gas tank mount and the tank itself, and then I get into the more technically challenging things like con rods and crankshafts. I'm building this engine in reverse---most times I recommend that people build the difficult engine parts first. If they can build the crankshaft, con rods, and valve train, then they can go on to do the easier large parts. Thank you to all who are following this build thread.---Brian


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## Brian Rupnow (Jul 5, 2022)

Holy Gas Tank Batmen!!!--There's a full days work in that gas tank and bracket, but I like it a lot.


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## Brian Rupnow (Jul 6, 2022)

Not a lot of new fabricating today, as I had some automation design to do for an old customer. However, I did get my new points and condensers and had to try them to make sure they fit, and I managed to pick up some oilite bronze bushings for my camshafts and the two idler gears.


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## dsage (Jul 7, 2022)

Hi Brian:
What vehicle do you ask for points from when you buy them. They must be getting scarce.
And where from - CTC?
Going to need two coils as well. Right?


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## Brian Rupnow (Jul 7, 2022)

The points are for a 1959 to 1972 Plymouth. I buy them from Partsource---and yes, they are "special order" items now. I think I can get by with one coil. Back in the day, a single coil ran 6 or even 8 cylinders.


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## Brian Rupnow (Jul 7, 2022)

Today was gear making day. Not terribly difficult but time consuming. Tomorrow I will add a bunch of set screws and get all of the gears meshing with one and other.


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## dsage (Jul 7, 2022)

Brian Rupnow said:


> The points are for a 1959 to 1972 Plymouth. I buy them from Partsource---and yes, they are "special order" items now. I think I can get by with one coil. Back in the day, a single coil ran 6 or even 8 cylinders.



Thanks for the source of the points.
As for the coil issue. I was referring to the wiring. I guess it will be wasted spark then. Will that work with the cylinder angle / valve timing etc.
Looking good..
Thanks


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## awake (Jul 8, 2022)

Points for various engines are readily available on Amazon. I've used points for old Ford tractors; I've seen others use points for Tecumseh engines or similar.


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## ozzie46 (Jul 8, 2022)

Brian I sent you a private message about when you first got your rotary table.

Ron


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## Brian Rupnow (Jul 9, 2022)

It will not be "wasted spark" ignition. The cams are running off the camshafts.


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## Brian Rupnow (Jul 9, 2022)

Yesterday the cam gears were completed and the engine was driven by an electric motor to wear in the gears for a perfect mesh. The camshaft support blocks were drilled for bushings and the cam shafts installed. The  ignition cams were made and installed. The ignition points were installed, but there was a fitment problem and I am going to have to redrill two holes and move them around a little bit.


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## dsage (Jul 9, 2022)

Brian Rupnow said:


> It will not be "wasted spark" ignition. The cams are running off the camshafts.



Hmmm. The arrangement should be interesting. Maybe I'm missing something. Two sets of points, driving one coil, with two spark plug cables from the same coil. How will only one cylinder fire at a time?

No need to elaborate. I'll stay tuned.


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## Brian Rupnow (Jul 9, 2022)

dsage--I may have to think that out a bit more. With only one coil and two sparkplug leads required, and no distributor to designate which plug is being fired, I may well have to go with two coils. Thanks for bringing it to my attention.---Brian


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## Gordon (Jul 9, 2022)

If I remember correctly you built a twin cylinder before and you used a dual coil with two spark plug cables. Lawn mower coil if I remember correctly.


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## Brian Rupnow (Jul 9, 2022)

No, actually it was a twin cylinder  snowmobile set-up, and it worked really well. Since the ignition is really a separate thing from the machined engine components, I haven't given it a lot of thought. If I were to incorporate a distributor that would direct which sparkplug the spark was going to, I could get away with one coil. This summer my main goal is to machine and assembly all of the engine components, then worry about the ignition after the engine is built. I may be getting the horse ahead of the cart here. I do have an extra 12 volt coil kicking around, and I do know I can make this system work with two sets of points and two coils, with no distributor required.


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## Brian Rupnow (Jul 9, 2022)

I keep redesigning and refining this engine as I build it. I'm almost at the point where I need to start building finned cylinder heads.---and I'm thinking how great they would look made from brass. Aluminum works, and works very well, but brass is sooooo pretty!!! I need a piece of brass flat bar 2" x 3/4" x 4" long to make two cylinder heads. On Monday I will call my metal suppliers to see what a piece of brass that size would cost me. I'm pretty sure that the last time I used it my 0.094" slitting saw blade (which I cut fins with) was dull as a hoe, so I'll probably need to replace it also. Tomorrow is scheduled to be a big backyard birthday party for my daughter and I (I just turned 76 and my daughter is turning 38) so a family party day will give me another day to think about this.


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## awake (Jul 9, 2022)

Hmm, never thought about brass for a cylinder head. I await developments with interest ...


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## Steamchick (Jul 10, 2022)

Brian Rupnow said:


> No, actually it was a twin cylinder  snowmobile set-up, and it worked really well. Since the ignition is really a separate thing from the machined engine components, I haven't given it a lot of thought. If I were to incorporate a distributor that would direct which sparkplug the spark was going to, I could get away with one coil. This summer my main goal is to machine and assembly all of the engine components, then worry about the ignition after the engine is built. I may be getting the horse ahead of the cart here. I do have an extra 12 volt coil kicking around, and I do know I can make this system work with two sets of points and two coils, with no distributor required.


Just for a comparison: I ride a Moto Guzzi V-twin V50II (from 1979). It runs a redundant spark arrangement without any problems. Quite simply, it is just easier and simpler than having a distributor. Using a SINGLE coil with a pair of HT cables is common for motorcycles that run redundant spark. The voltage goes from HT cable 1 to HT cable 2. When Cylinder 1 is approaching compression, with gas n air at near full compression, the spark at 1 uses most of the volts across that spark gap, then through the engine, and uses the last "10%" of volts to jump cyl 2 plug to the HT lead - which is not at compression, so doesn't fire. Then the similar action occurs when the cam and points fire again for the timing for cyl 2 to fire. Simply, it just works, so don't worry about "how", just do it. A single points cam with 2 "firings" is needed, from 1 camshaft. The single low tension power then fires the "double-ended" single coil single coil, with an HT lead to each spark plug. 
Good stuff Brian.
K2


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## Steamchick (Jul 10, 2022)

Hi Brian, "my 0.094" slitting saw blade (which I cut fins with) was dull as a hoe"... I bought a diamond "file" - only 1/4" wide, and meant for sharpening kitchen scissors and the like. It sharpens all my tool  - for lathe, Miller, etc. if the edge is just "dull"... 1 or 2 strokes per tooth should restore the teeth on the slitting saw blade. And may be easier and cheaper than a new blade? 
For use on Brass, I would want a finer tooth and faster cutting speed  (perhaps?) than for aluminium? But I'm sure you have all the tables to decide the correct tool.
K2


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## dsage (Jul 10, 2022)

Steamchick said:


> Just for a comparison: I ride a Moto Guzzi V-twin V50II (from 1979). It runs a redundant spark arrangement without any problems. Quite simply, it is just easier and simpler than having a distributor. Using a SINGLE coil with a pair of HT cables is common for motorcycles that run redundant spark. The voltage goes from HT cable 1 to HT cable 2. When Cylinder 1 is approaching compression, with gas n air at near full compression, the spark at 1 uses most of the volts across that spark gap, then through the engine, and uses the last "10%" of volts to jump cyl 2 plug to the HT lead - which is not at compression, so doesn't fire. Then the similar action occurs when the cam and points fire again for the timing for cyl 2 to fire. Simply, it just works, so don't worry about "how", just do it. A single points cam with 2 "firings" is needed, from 1 camshaft. The single low tension power then fires the "double-ended" single coil single coil, with an HT lead to each spark plug.
> Good stuff Brian.
> K2


Steamchick:
The system you describe is "wasted spark". But as you noted in your last sentence,  it requires a double ended coil (no ground reference). Brian can't do that with one "standard" coil as he plans. The easiest solution would be to purchase a wasted spark (double ended) coil from a modern car. It would be cheaper than two single coils and less clumsy.
Then there is still the issue of valve timing and where each cylinder is in it's cycle. Only Brian can answer that based on his design. i.e you wouldn't want to fire the non-compressed cylinder on it's intake stroke.


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## stevehuckss396 (Jul 10, 2022)

When I built my compressor engine I bought a snowmobile coil that was for that purpose.  The cdi systems we use for the mini engines had no problem getting it to fire. Fond them on Amazon or ebay. They were dumping old stock and were less than 10 bucks. Maybe see if they are still out there. Pretty sure they did not work at 12 volt so make sure it is what you want.


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## dsage (Jul 10, 2022)

And a FINE engine it is Steve.


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## stevehuckss396 (Jul 10, 2022)

I would need to go through my notes but that coil is super simple for a wasted spark engine.

I just did a search and they are around 35 bucks now.


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## Brian Rupnow (Jul 10, 2022)

This morning before we got into birthday party mode, I spent an hour reconfiguring the cylinder head so it can be machined from a piece of 2" diameter brass. Actually, the finished part is 1.9" diameter, same as the outer diameter of the cylinder. I will look at it more closely tomorrow morning to make sure I haven't missed something. If all looks okay, then the cylinder heads will be brass.


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## animal12 (Jul 10, 2022)

I keep looking at your in post 74 & your in the neighbor hood for a Harley 45 flathead engine tough they used 4 cams but I think I can see where it can be done with one cam & some relocating of the valve setups . 


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## Brian Rupnow (Jul 11, 2022)

Animal---I know that it can be done with a single cam running in the center. I chose to do it with the double cam as I am showing it. Thanks for your suggestion.---Brian


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## Brian Rupnow (Jul 11, 2022)

_If the hole pattern in the block and head match, just drill the hole through the cylinder. Use long screws to hold the head on that go all the way through the cylinder into the block. I have always liked the way that looks._
Steve Hucks--your suggestion of using long bolts to reach from the top of the cylinder head, thru the cylinder, and screw into the crankcase has a lot of real advantages. I just checked and I would need #5 socket head capscrews x 3" long to do that. Can you buy #5 socket head capscrews x that long?---Brian


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## stevehuckss396 (Jul 11, 2022)

Yes sir. McMaster Carr has #5-40 listed up to 3 inch long. If you need help getting them I can help with that for cost plus shipping with no additional fees. Let me know of you need anything. 

Check grainger also. I can drive over there and get them and send them to Canada for 14-16 bucks depending on the mood of the Usps. If you get a whole box it might be more because of the weight.


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## Brian Rupnow (Jul 11, 2022)

I checked my McMaster Carr catalogue, and the 3" long shcs are full thread. Do you know of anywhere that sells them not fully threaded?


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## Vietti (Jul 11, 2022)

Why not get some leaded, 1/8" rod and make studs?  You can locktite either end and have studs or bolts, I'd go the bolt route.  Even if you find a source for the bolts you want, they might be$$$, esp if you have to buy a box of 100.

5/40 is my favorite thread.  Material is easy to source and the pitch seems agreeable, not too fine, not too coarse!

Enjoying the build.

John


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## Brian Rupnow (Jul 12, 2022)

Vietti--a closer look shows me that I will have to save this idea for a future engine because of clearance issues. Thank you for the idea.---Brian.


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## Steamchick (Jul 12, 2022)

Hi dsage: Your point "Then there is still the issue of valve timing and where each cylinder is in it's cycle. Only Brian can answer that based on his design. i.e you wouldn't want to fire the non-compressed cylinder on it's intake stroke." - is correct. 
But when the mixture is right and ignition timed for the correct BTDC, then the compressed fuel-air mixture is heated by the compression, much denser than "at open inlet" and therefore ignites readily, whereas the same spark (current, not voltage) travelling across the contacts in the cylinder with open inlet valve does not have the same voltage to ionise the gases and promote ignition, the mixture is not pre-heated by compression to promote ignition, and the Stoichiometric mixture is simply not able to be ignited. - One of the reasons for a "Choke" on cold engines is to make the mixture rich enough when the "cold stoichiometric air-fuel mix in a cold cylinder" won't otherwise ignite.
Anyway, whatever the theory, I have never had a spit-back through an open inlet valve on my Guzzi... so I think it works...?
K2


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## Brian Rupnow (Jul 12, 2022)

No machining progress today----But---I took a very deep breath and went into my metal suppliers and bought 2" diameter brass to make cylinder heads and gas-tank ends, a piece of 1144 stress proof to make a crankshaft, a piece of 1/4" cold rolled flatbar to make a changed ignition points bracket, and a piece of 0.040" brass sheet to cover up a machining boo boo that I made on the crank-case. That little handful of metal cost $75. I can see a time coming when I have to start making engine parts out of rocks or something.


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## stevehuckss396 (Jul 12, 2022)

Sorry Brian but cool ain't cheap.


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## Brian Rupnow (Jul 12, 2022)

You are so right!!!


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## Brian Rupnow (Jul 13, 2022)

So, here we go!! Cylinder head machining step one. The two inch diameter brass has been turned to 1.9" diameter, set up in the rotary table 3 jaw chuck, zeroed out under the quill, and all of the holes drilled .8125" deep. (The finished head thickness will be 0.75".) The holes for the #5 shcs have been counterbored 0.297" deep, which is the same as the depth of the cuts between the fins. The valve cage holes have been drilled and reamed to finished size, but still have to be counterbored on the far side to accept the flange on the valve cages. One hole gets tapped #5-40 for a shcs which will eventually hold the rocker arm tower. The spark-plug hole will be drilled and counterbored in a future step, as will the flat on one side of the cylinder head. the rotary table is not being turned for these steps. It is simply acting as a holding fixture. Next step will be moving back over to the lathe to part off the first cylinder head so the radial groove for the o-ring head gasket, the counterbore for the valve cage flange and threaded hole for the sparkplug can be added.


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## Brian Rupnow (Jul 13, 2022)

And as we get farther into it--- The counterbores have been put into the inside of the cylinder head to accept the flanges of the valve cages. The annular groove for the viton o-ring head gasket has been cut, the flat has been machined on one side to accept the intake flange, and the scariest part of all is the sparkplug hole drilled, tapped, and counterbored. This is very scary, because you are working blind. You follow all the dimensions and really, really hope that it breaks thru in the correct place, inside the annular groove and clear of the valve cage counterbores. The holes for the intake, exhaust, and intake flange won't be put into the head until the valve cages have been loctited into place. Tomorrow I get to do this all over again, only opposite hand.


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## Brian Rupnow (Jul 13, 2022)

It fits!!!


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## stevehuckss396 (Jul 14, 2022)

Never a doubt!


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## Brian Rupnow (Jul 14, 2022)

I was away from home most of the day, but my old brain never stops ticking. I was thinking of how to hold the cylinder head accurately and rigidly to machine the flat area where the rocker arm tower bolts on, and to put the slots in to make cooling fins. I decided that I needed a fixture to hold it properly, so when I got home I grabbed a piece of 2" square aluminum stock, squared both ends in the lathe, and drilled and tapped the bolt pattern to match the cylinder head. Now I can hold the head exactly where I want it to perform follow on operations and not have to worry about my set-up moving in the middle of the operation.


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## Ghosty (Jul 14, 2022)

Brian,
I done the same thing when I was machining the heads for the twin I built. Mine a piece of round bar as it was to be held in chuck of lathe and dividing head, Pic shows in lathe machining the cooling fins, last operation.
Cheers
Andrew


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## Brian Rupnow (Jul 15, 2022)

Got up this morning all bright eyed and bushy tailed and decided to mill the flat spot on the cylinder head where the rocker arm tower bolts on.  I can't cut the cooling fins in right now, as my 3/32" slitting saw is dull. A new slitting saw costs $53 but it only costs $12 to have the old sawblade sharpened. He lives so far from me that it would offset any cost benefit to drive there, but he picks up and delivers in Barrie once a week. I can't do anything else on this cylinder head for now, so will spend today machining the other opposite hand cylinder head.


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## Brian Rupnow (Jul 15, 2022)

I put my 4" length of brass to good use. It has made two cylinder heads and two gas tank ends. I have much grinding and sanding to do to finish the tank, but I like it. It is all ferrous metal and all silver soldered except for the two brass ends which will be held in place by J.B. weld. And if you see that the gas tube enters at the center of the tank, don't be alarmed---it bends 90 degrees just inside the tank and reaches down to the tank bottom.


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## metalmangler (Jul 16, 2022)

Brian Rupnow said:


> It is all ferrous metal and all silver soldered except for the two brass ends which will be held in place by J.B. weld.


I'm curious - why not silver-solder the tank-ends as well ? Do ferrous metals and brass not stick together when silver-soldered ?


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## Brian Rupnow (Jul 16, 2022)

I could have silver soldered the tank ends. I have done it in the past. I have found though, that there is always at least one spot that will always leak and one place where the silver solder runs over onto the brass, and it becomes a pig to clean up, not leak, and look right. J.B. weld does the same good job of holding the ends in place and I've never has a clean up or leaky issue doing it this way.


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## stevehuckss396 (Jul 16, 2022)

Have you tried soft solder? I have made 4 or 5 tanks an always use soft solder and a little Flux. 

I Flux everything and put a ring of solder right at the edge of the tube and use the end cap to push the ring in. Then just heat until you see solder just starting to appear in the joint all the way around. Zero mess and just a little polish to remove the heat marks.


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## Brian Rupnow (Jul 16, 2022)

I haven't worked with soft solder, and if I was really good with the tig welder I would have tig welded everything. I can stick things together with the tig, and get good penetration, but cosmetically it will be a disaster. This morning I spent an hour with my file, sandpaper, and polishing buffs and various wax grits, until I deemed things satisfactory, then J.B. welded the brass ends into the tank and set it up in my outer garage vice to dry 24 hours.


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## Brian Rupnow (Jul 16, 2022)

Today, for the first time, the flywheel is in place and the rocker arm towers have been added to the top of the new cylinder heads. I hadn't planned on doing so much today, but it's not my first day that didn't go as I planned. I'm liking the look of this!!!


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## stevehuckss396 (Jul 16, 2022)

Good call on the heads. They look real good next to the flywheel


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## Brian Rupnow (Jul 16, 2022)

Thanks Steve. I love the look of accent brass.


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## Brian Rupnow (Jul 17, 2022)

We're getting down to the short strokes now. Today I'm doing a search for simple easy things that have to be built. I've found four valve lifter bushings, four hardened rocker arm tips,  four rocker arms and four valve lifters. I'm going to take a look at the rocker arms right now and see if they can be simplified a bit. I am currently using the rocker design used on my 7/8" horizontal engine.


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## Brian Rupnow (Jul 17, 2022)

Today I managed to get the valve lifter guides machined from brass and Loctited in place. I machined and flame hardened the valve lifters and the four contact wheels that fit onto the end of the rocker arms, and I got the rocker arms cut to length but not machined yet. Doesn't look like much, but it's 4:30 now and I started this morning at 8:00. Stopped at 12 and eat some lunch, stopped at 3:00 and went up onto my top deck with my good wife and had a wine cooler break. Tomorrow I hope to finish and install the rocker arms.


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## Brian Rupnow (Jul 18, 2022)

Today I did more running around town than I did actually working, but I did manage to finish the four rocker arms and four knurled adjusting "knobs" and got them "mocked up" in place.


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## Brian Rupnow (Jul 18, 2022)

The hackers are having their way with me. I just wrote a big long post, and when I submitted it I got a big yellow and blue "anti-war" post. Pisses me off to no end, and I'm not going to re-write the post i lost.


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## Ghosty (Jul 18, 2022)

Brian,
I write a lot of my posts in "Word", especially the long ones, then copy and paste, I also save a copy in the build folder with the pics
Cheers
Andrew


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## minh-thanh (Jul 19, 2022)

Engine color looks pretty   !


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## Brian Rupnow (Jul 19, 2022)

It is very seldom that I have to remake parts. I hate it worse than snakes, but sometimes you gotta do what you gotta do. Today, I remade the bar which the ignition points are mounted on. The first one I made (shown in the picture) wasn't machined incorrectly. It was designed incorrectly. A bit of investigating showed what the problem was. This bar was based on the fact that gears are SUPPOSED to mate exactly at the theoretical pitch diameters. My gears mate very well, but probably not on the exact pitch diameters. Normally that wouldn't matter, and it doesn't affect how the engine will run, but there is enough difference that it screwed up the dimensions on the bar. Things have been fixed now, and my ignition points open and close how they are supposed to. I also took the opportunity to mount the gas tank and tank support back onto the engine.


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## SteamChEng (Jul 20, 2022)

Engine is looking really good, Brian.  I am always impressed with your casual skill in machining what you designed.  Probably would have taken me three times as long and several "do-overs" on the way.


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## Brian Rupnow (Jul 20, 2022)

Both cylinders have been removed from the engine and lapped. That is an acro-lap laying in the foreground. It was so difficult to get the bolts out that held the cylinders to the crankcase that I machined 0.200" off the diameter of the bottom cooling fin to give me better wrench access.


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## Brian Rupnow (Jul 20, 2022)

This is the "Big cover Up". When I machined the crankcase, I got a bit too enthusiastic when milling the flat spots that the cylinder sets on, and as a result had some very visible nasties machined down past the counterbore in the sides of the crankcase, right up on top where they would show. Didn't affect how the engine would run, but looked awful. There is a lot of work in that crankcase, so rather than build another one, I scored a piece of 0.040" thick brass, and with a bit of creative cutting and carving, it fits between the base of the cylinders and the top of the crankcase, and hides the uglies.


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## ShopShoe (Jul 21, 2022)

Brian,

Just another reason why I like your projects.

Your original designs mean that they can be whatever you want them to be and you don't have to meet anyone else's concept of "correct."

I also admire your long experience as a designer and builder which helps you keep going despite some setbacks.

On this one, a little more brass only adds to the appearance: I like it.

--ShopShoe


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## Brian Rupnow (Jul 21, 2022)

Thanks Shopshoe.--Today I'm building a crankshaft. Stress proof 1144 is only available in rounds, so the first operation is to slab off both sides so that I have a flatbar to start my work on. This first side can be done on the mill or on the bandsaw. I prefer to do it on the mill, so I have a "witness side" to run along the bandsaw fence. It can also be cut on both sides with the bandsaw, but I prefer this method.


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## Brian Rupnow (Jul 21, 2022)

And after what seemed to be an awfully long day, I have a finished one piece crankshaft from 1144 stress proof steel. The day wasn't really THAT long--(I was out and about doing things this morning and had a visiting guest this afternoon.) Crankshaft was turned between centers, has no really measurable run-out. I wish that I was a good enough machinist to turn to a bearing fit. After you've ruined a couple of crankshafts by ending up undersize, I leave my crankshafts about .0015" oversize, then spend what seems like ages with sandpaper strips bringing them down to a perfect bearing fit.


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## Steamchick (Jul 22, 2022)

I am sure others learn a bucket load from your simple comments. I certainly do!
Thanks Brian. Reading your posts has a therapeutic effect on me, knowing there is a "Good man, with Good machines, making Good stuff!" (I like Good!).
K2


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## Brian Rupnow (Jul 22, 2022)

Today is going to be "piston day", and it is going to be a piston with a difference. Whenever I used viton rings (one per piston) I always got immediate compression and my engines started with no muss, no fuss.  If instead, I made and used cast iron rings, the problem always seemed to be to get enough initial sealing for the engine to start. Once the engine started, it only took a short time for the rings to "wear in" and provide a good strong compression seal. After giving this some thought, I decided "What if we used both types of rings?--The viton ring would give great initial sealing to get the engine started. Once the engine started and ran for half an hour, the two cast iron rings would "wear in" and provide a good compression seal. After that, the viton seal ring would become redundant, but could stay on the piston, doing no harm. Pistons are relatively easy to make, and I think my idea has merit. So, on the piston, as I have modelled it, the top two rings would be cast iron heat treated conventional rings, and the ring groove just above the wrist pin will be a 1/16" cross section Viton o-ring.


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## Vietti (Jul 22, 2022)

Very interested in the outcome of your piston ring experiment! 

I appreciate your willingness to experiment and perhaps fly in the face of conventional wisdom.


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## Brian Rupnow (Jul 22, 2022)

--Viton rings are heat proof, work fine as piston rings, and always seal  100% right from as soon as they are installed. The nominal ring cross section is 1/16" and the o.d of the ring should match the bore of the cylinder. The groove in the piston is 0.094" wide and 0.059" deep, and you only need one ring per piston. Yes, I do make my own cast iron rings, have posted extensively about it on this forum, and bought a heat treat oven to "set" the rings over an expanding fixture. I have indifferent success with my cast iron rings. Sometimes they seal great, other times not so much.---Brian


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## Brian Rupnow (Jul 22, 2022)

And now---Lapping a piston. The cylinders had been honed with an Acrolap, and measured about 0.8752 inside. I chucked up a piece of 1" cast iron in my lathes 3 jaw chuck, and turned the outer diameter to 0.876", going very slowly and checking often with my micrometer so as not to turn it undersize. I turned the piece of grey iron to about an inch longer than the two 1" pistons would be. Then I coated the iron with 600 grit lapping paste, and with my lathe running at a very low speed I worked an internal split lap which I made from brass back and forth over the full length of turned shaft, progressively tightening the screw, which closed the lap in very small increments, until I had removed enough stock that the iron piston would just begin to slide into the cylinder. At that point I recoated the iron with 600 grit lapping paste and holding the cylinder firmly in my hand I slowly worked it back and forth until the entire machined length of the cast iron round bar would fit all the way through the cylinder. You have to be prepared to let go immediately if the cylinder starts to seize onto the rod, shut the lathe off, and work the cylinder loose, then carefully start again. Once the cast iron rod passes the the cylinder, you are finished the first step.


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## Brian Rupnow (Jul 22, 2022)

The bottom counterbore has been added to piston #1, and the ring grooves cut. The piston will now be parted off, and tomorrow a deeper slot below the counterbore and the wrist pin hole will be added.


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## stevehuckss396 (Jul 22, 2022)

Why cast pistons brian? Why not aluminum? Lighter and less stress on crankshaft and connecting rods.

Just curious.


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## Brian Rupnow (Jul 22, 2022)

Cast iron has a lot of graphite in it's make up. This makes it self lubricating to a great extent. Aluminum has a much higher heat expansion factor than iron does, which means that you have to leave greater clearance between the cylinder and piston so the piston doesn't heat seize. Aluminum is great for high speed engines because it weighs only 33% of what iron does. I like my engines to run slower, so the heavy pistons don't really matter---in this case.


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## stevehuckss396 (Jul 22, 2022)

Copy that thanks for the info.


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## Brian Rupnow (Jul 23, 2022)

Today I finished the pistons. No real problems encountered, just a couple of different rotary table set-ups.


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## Brian Rupnow (Jul 23, 2022)

Tomorrow I get to do something exciting. I get to start machining my knife and fork style connecting rods. I have never built knife and fork rods before, and I find the concept to be quite intriguing.


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## Brian Rupnow (Jul 24, 2022)

Okay kids, hold on tight, here we go with our first machining step on the fork style con rod. The block of material has been milled to size, and out first step is to put in two holes and to cut the slot that the "knife" style con rod rides in. The 1/4" radius where the con rod narrows  will fall partly outside the material. Can't drill half of a hole, so a piece of scrap material has been positioned on each side of the blue block, which lets me drill a thru hole with a 1/2" diameter bit.


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## Brian Rupnow (Jul 24, 2022)

The wide end of the con rod has an angle leading off from the 1/4" radius to the outside of the part. I set the part up in my vice and use my digital angle finder to set it at the correct angle, then come in and machine the corner down until the flat I am creating falls tangent to the 1/4" radius. This is done once on each side of the fork style con rod.


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## Brian Rupnow (Jul 24, 2022)

The con rod has been taken down to final dimension on "first side". Next machining step is to begin machining the second side.


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## Brian Rupnow (Jul 24, 2022)

Now we turn the material 90 degrees and machine the second side. Once again the 1/2" diameter holes where the con rod begins to narrow will fall partly outside the con rod material, so once again we have a piece of scrap aluminum clamped on both sides of the con-rod so as not to drill holes thru my vice jaws. The 3/16" wrist pin hole has been drilled and reamed, and two smaller holes which form the radius tangent to the sides of the con rod have been drilled. The hole for the crankshaft journal will not be put in until the con rod caps are finished and installed.


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## Steamchick (Jul 24, 2022)

Hi Brian,
I see on the drawing there is a radius on the inside corner of the slot to make the fork. What size do you use? I was involved in a design job in the early 80s, where we cured "stress fractures" with changing the radius from 1 mm to >3mm - as even 2.5 mm could be failed after enough cycles. But we ran out of "life" for testing the 3mm radii corners. - In fact to help the plant we specified 1/8in cutters to generate the corners. (They had surplus imperial tooling!). But the major issue was getting a clean smooth transition from radiused corner to flat face. Then all our troubles disappeared...
Cheers! - Your work is just excellent. Thanks for the tutorials!
K2


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## Brian Rupnow (Jul 24, 2022)

And here we are--This con rod is almost finished. I still have to drill and tap four holes in the big end for the con rod cap bolts. I started this morning at 7:00 and it's 2:00 now. take out an hour for breakfast and lunch, and there's still 6 hours work in this con rod. I might get the caps done this afternoon if I don't take a lazy spell.


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## Brian Rupnow (Jul 24, 2022)

Steamchick--you've caught me out on something that few people notice. When I make these component details, I do so blindingly fast. Then, days later, when I go to actually machine the part, it is common to find that I have left a dimension off the drawing. That's okay, it only takes me seconds to add the dimension, because the math data has all been entered when I designed the 3D cad model. Knowing that I will probably sell a few sets of the plans to builders around the world, I add the missing dimensions as I discover them. I can do this with my software, but people who buy plan sets from me can't because they receive .pdf files, not my original Solidworks files. My cad program costs about $7000, which was a legitimate write off for me and my business, Rupnow Machine and Automation Design. No one building small engines as a hobby wants to eat that kind of cost, so the drawings are sent out as pdf files, and anybody can open them.---The rad is 0.060".


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## Brian Rupnow (Jul 24, 2022)

So, the fork style con rod is finished and so are the two rod caps it requires, and bolted in place on the crankshaft. There is a full 8 hours in this con rod and caps, and I'm quite happy with the way they turned out. Tomorrow I will tackle the knife style con rod that rides on the same journal and fits inside the slot in the fork style con rod.


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## Brian Rupnow (Jul 24, 2022)

---I won't really know for sure until tomorrow, but I may have to cut an access hole in the bottom of the crank case, to tighten the rod caps onto the rods. Things are starting to get very crowded in there.   Trying to install and tighten con rod cap bolts when you can only swing the allen wrench in a 25 degree arc is kind of like banging your head against the wall.


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## Steamchick (Jul 25, 2022)

Hi Brian, Thanks for that reply #144. I wasn't "catching you out" in any way for a missing dimension, though I'm sure it will be on the plans when published. I was simply curious, but professionally impressed that you had considered this and added a stress relieving radius. To few think of these things, that are second nature to professionals. But to anyone making your design these things are also very important to follow. I guess you simply had the radius on the milling cutter that milled the slot? - Milling from the "Big-end" of the conrod? - Too many would have used a sharp-cornered cutter, perhaps to their demise?
Well done and thanks for the reply.
K2


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## stevehuckss396 (Jul 25, 2022)

Would it be possible to assemble the rods on the crankshaft, slip the bearing onto the crank, slip the crank into the case and get the rods up through the cylinder holes, then align the crankshaft and insert the bearing into the case?


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## Badhippie (Jul 25, 2022)

Brian
How are you going to control the side to side play between the blade rod and the fork rod. We used a very similar set-up on EMD engines. Only there is a slot machines into the inner radius of the fork rod that the machined edge of the blade rod rides in. Then the fork rod is a basket design that bolts to the sides of the fork rod. Then the rod brgs are pegged to the fork rod. So that the rod brg rotates with the fork on the crank pin. And the blade rod rides on rod brg. When I get home tonight from work I’ll send some pics that will explain it better 
Thanks Tom


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## Brian Rupnow (Jul 25, 2022)

Now this is a beautiful thing!! The second con rod and cap took only three hours to make, and an hours fussing and fitting to get crank, rods, rod caps and pistons to all go together nicely. I'm liking it!!!


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## Brian Rupnow (Jul 25, 2022)

Stephenhuckss----I thought you might be onto something there with your suggestion, but no such luck. (I just tried doing it). I'll put an access hole in the bottom of the crankcase. I don't have any large taps so my access hole will have to have a cover that bolts on with perimeter bolts.


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## Brian Rupnow (Jul 25, 2022)

Things are back together, and it all fits ---and that's a good thing. I can't rotate the crankshaft thru a full 360 degrees because I'm getting some interferance between the connecting rods and the bottom/inside of the cylinders. I did end up drilling a 1.25" diameter hole thru the bottom of the crankcase to let me tighten the con-rod cap bolts. Tomorrow I will sort out the clearance issues.


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## Brian Rupnow (Jul 26, 2022)

All interferences have been removed, and the crankshaft rotates thru a full 360 degrees without any solid stops along the way. It is very stiff, but the stiffness is being addressed in this video.


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## Brian Rupnow (Jul 26, 2022)

The engine has been "run in" until the crankshaft will turn freely with the rod cap bolts tightened down. Hopefully, I can get my 0.094" slitting saw back from sharpening this week, and cut the cooling fins into the cylinder heads. I have to make a bolt-on plate to cover the hole in the bottom of the crankcase, and have to put a hole in the side of the crankcase for an oil filler pipe.----This engine will have oil in the base for splash lubrication of the connecting rods and wrist pins. I haven't made the valves or the valve cages yet. There will be a pair of gear guards made to cover the camshaft gears, but I won't make them until after the engine has been ran. Probably will be ready to start the engine by mid August.


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## Brian Rupnow (Jul 27, 2022)

So, what do you do when you've cut a great big hole in the engine crankcase to give wrench access to the rod cap bolts? Well of course, you make a cap plate that screws onto the crankcase hole to give it  leak proof cover. This of course means milling some material away on both of the crankcase support feet so that the cover plate can be taken off in future without having to remove the crankcase feet to do so. Now I'm off to the hardware store to see what they have in small diameter black iron pipe that might work for an oil filler spout.


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## Brian Rupnow (Jul 27, 2022)

And after a visit to my local hardware store, I came home with sufficient pipes and elbows, etc. to make my oil filler tubes from.


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## Brian Rupnow (Jul 28, 2022)

Now we have a place to put the new oil in, and a slightly lower place that the oil starts to run out of when the crankcase has the right amount of oil in it. Somehow, this was far more difficult than I had assumed it would be, but it's done---even if it did take me an entire morning to do it. Sid suggested that the oil level in the engine should be lower than I initially planned, so I dropped the oil level another 1/4" from where I had originally intended it to be.


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## Steamchick (Jul 28, 2022)

Hi Brian. Splash Systems consume loads of power, so an oil level just below the crank and con-ròd is OK with a small - say 1/8" diameter or smaller by 1/4 to 1/2 in long rod fixed in the bottom of the con-rod to just hit the oil and cause the splash is adequate.
K2


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## Badhippie (Jul 28, 2022)

Brian 
Oil is like exercise its over rated. 
Just having some fun the build looks great can’t wait to hear it run


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## Brian Rupnow (Jul 29, 2022)

Now I have to ask Is that a beautiful thing, or what? I had a bad attack of lazy yesterday afternoon so I drove down to Alcona and picked up my sharpened slitting saw from my tool sharpener man. He does great work. This morning I cut the fins into my cylinder heads, and I'm really happy with the results.


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## stevehuckss396 (Jul 29, 2022)

Yes it is!


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## Joe (Jul 29, 2022)

Brian Rupnow said:


> Now I have to ask Is that a beautiful thing, or what?


Well yes indeed,  the contrast of brass and steel, the balanced symmetry all blended brilliantly with the red necked cludgery of the Home Depot oil filler.


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## Brian Rupnow (Jul 29, 2022)

That isn't a Home depot oil filter. That tool, which is just resting on a piece of cast iron, has a counterbore that just fits my dies. The other end isn't a socket, it's just a round sleeve that slides over a piece of round steel held in my tailstock.


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## Steamchick (Jul 29, 2022)

That's a pretty engine. Really looks right!
K2


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## Badhippie (Jul 29, 2022)

It looks damn fine and looks like it’s just a few hours from running


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## Brian Rupnow (Jul 29, 2022)

This afternoon we have four valve cages---two for each cylinder. They are not yet ground for the valve seats and they don't have the hole thru the side yet that aligns with the cylinder head ports. They are inserted into the heads with a light push fit and 638 Loctite. They will be ground to accept the valves 24 hours after the Loctite was applied and the port holes will be drilled in the cylinder heads and the valve cages at the same time.


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## Brian Rupnow (Jul 30, 2022)

This morning I made the four valves for the v-twin engine. they look a little funky right now, because I left the "handles" on. After each valve is lapped into it's own particular seat, the valves will be match marked with the valve cage they fit in, and the handles will be cut off.


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## Brian Rupnow (Jul 30, 2022)

So, we're coming down to the wire on this build. Tomorrow I will lap the valves, cut off the handles, and cross drill the ends of the valves for valve spring retainer pins. Will probably also make the valve spring retainers tomorrow. Then I can drill the inlet and exhaust ports in the heads, and drill and tap them for the intake manifold bolts. I need to put a keyway in the crankshaft, and I have to design/build a starter hub. I may build and install a gear guard, although it isn't necessary to run the engine. I haven't done anything yet on the intake manifold/fan mount.----And I need to machine four cams.----And exhaust pipes.  I may have to build a crankcase vent valve, but I'm not sure yet. Still have to make proper rocker arm shafts with a c-clip groove on each end. So, probably another couple of weeks work yet.


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## Brian Rupnow (Jul 31, 2022)

Today I had a very lazy day. That's not usual for me, but when I'm lazy, I'm lazy. I lapped the valves into their seats, trimmed off the handles, and cross drilled the ends for retainer pins. I hunted around in my box of spare parts left over from other builds, and found a couple of valve springs, and four valve spring retainers. (Two of the retainers need a skim taken off the o.d. and that is why they are loctited to a 1/8" piece of rod, so I can hold them in the lathe tomorrow and do that). I had great intentions of drilling the ports into the heads and drilling/tapping the intake manifold threads, but I went and laid down for a nap instead. Today I'm a lazy bum!!! Tomorrow I will finish the heads.


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## Brian Rupnow (Aug 1, 2022)

The valves, springs, retainers and cross pins are finished and the heads are now completely finished. I will bolt on all of the rocker tower supports, axle pins, and rockers next. You will see that I had to move a set of tapped holes where the intake manifold connects to the heads. I had a pair of tapped holes interfering with one of the head bolts, so I moved the tapped holes and updated the drawings.


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## Brian Rupnow (Aug 1, 2022)

Well, so far, so good.


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## SteamChEng (Aug 2, 2022)

Man, that looks really sharp, Brian!


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## Brian Rupnow (Aug 2, 2022)

Thank you SteamChEng---
Today things slowed down a little. I wasn't getting enough clearance between the head of the valve at "fully open" and the top of the piston at tdc. I didn't plan on having one of those zero clearance engines, where if it jumps time then the valve goes thru the piston. This issue was solved by putting a 0.100" thick spacer between the bottom of the cylinder and the crankcase. I took a quick look at my bin of mystery metals, found something close to the right size, and didn't realize until I was machining it that it was 303 stainless. That's okay---almost any metal would have worked. I also machined a starter hub. Right now I have both cam shaft supports removed to give me better access to the bolts which hold the cylinders to the crankcase.


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## Brian Rupnow (Aug 3, 2022)

This is where I'm off to next. The carburetor is a purchased carburetor. The fan and fan shaft are supported by two 3/16" i.d. x 3/8" o.d. sealed ball bearings which are sold as router guide bearings. The center part is turned from brass. The trick of course will be to purchase and bend the two curved pieces. PartSource Automotive sell a metal brakeline that has the same inner and outer diameter as I have used, and I have a reasonably good tubing bender that accepts that diameter of tubing. The part I'm not sure about is what radius my bender makes.--I'll know tomorrow when PartSource opens.


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## Brian Rupnow (Aug 4, 2022)

What did I do on the engine today?--Not that much. I took two grandsons swimming at a nearby lake. Geez the water was cold. I bought a new 1/8" carbide end mill and cleared some obstructions out of the cylinder heads where the head bolts go thru. I bought a length of rigid brakeline to make the two bent intake manifold pipes. I redesigned the gear guards into something that will be a little easier to make, and I spent some time making changes on the fan mechanism because the 1/8" ball bearings that I used originally are no longer easily available.


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## stevehuckss396 (Aug 4, 2022)

That sounds like a little bit more than "not that much".


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## Brian Rupnow (Aug 4, 2022)

I haven't had stellar results bending my intake manifold tubes. I bought a length of steel brake line from PartSource, my local auto parts store. This is what I generally use to make bent tube assemblies from. The one on the right was a total failure using the red tube bender beside it. It kinked and that was that. The one on the left was bent using one of those wound spring bending devices, and although it didn't kink, it flattened out considerably in the bend area. I'm too cheap to buy a container of Ceramet which is a very low melting point metal which melts in hot water, can be poured into the tube, where it rapidly solidifies and then you can bend the tube without it kinking or flattening out, then just heat the tube in hot water and pour the liquified Ceramet out. I've bent these brake lines before with no trouble, so I will have to go down to PartSource tomorrow and see if there is a different grade of brake line that is more bendable. I was in a hurry today, and they had moved the stuff I generally buy to a different part of the store, so I may have picked up the wrong kind of brake line.


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## werowance (Aug 5, 2022)

for what its worth - im guessing you already know this but i have used sand to fill tubes before bending and that works really well.  i have also used ice.  fill the tube with water, freeze it (allowing one end to be open for expansion so it doesnt burst the tube) and that worked well.   i saw the ice method on a tv show called "how its made" and they were making trumpets and that was one part of the bending process


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## Brian Rupnow (Aug 5, 2022)

I don't doubt for a minute that it worked----for you. For me, not so much.


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## Brian Rupnow (Aug 5, 2022)

Okay---as I thought, I had purchased the wrong type of rigid brake line first time around. This morning I went back to PartSource and bought a length of copper nickel line. I bent two pieces on the right with the red mechanical tubing bender, and although they bent without kinking, the bends were very lumpy looking. Then I bent up a second pair of tubes with the silver coil spring tubing bender. This gave a very satisfactory bend with no kinking and very little flattening.


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## werowance (Aug 5, 2022)

lol,  yeah i should have said it has helped with "SOME" things i was having trouble bending.  its certainly not a perfect make everything bend like you want everytime solution.  just helped on a thing or 2 that i kept messing up.


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## Brian Rupnow (Aug 6, 2022)

I've changed my mind three or four times about what to do for a gear guard. Gear guards on these little engines do more than protect fingers---they cut down a lot of the noise created by the gears. Yesterday I finalized the design of the gear guard, and this morning I bought a piece of aluminum to make it from. We spent part of today returning a visiting grandson to Orangeville, and I got a good start on my guard this afternoon.  I have the final shape laid out, but won't finish machining it until tomorrow. I'm trial fitting this part as I go along, because the finished engine always has minor differences from the engineering drawing. So far, it's fitting the way I had planned.


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## Brian Rupnow (Aug 6, 2022)

And Presto!!!---We have a beautiful new gear guard. Lot of work in that puppy, but it looks good.


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## Steamchick (Aug 6, 2022)

Hi Brian, Having bent many tubes with a variety of benders - like you have been doing - I think your explanation shows "Why" I have some success and some failures! = "Wrong material" of tubing. 
I have filled copper tubes with plumbers' lead solder, (successfully), Candle wax (Good and easy), sand (difficult and needs ends blocking and good compression of the fine sand), and have heard that fine sugar, (Icing sugar? Castor sugar?) works, but not tried it. Also, I was told that caramel works (melted sugar with a dash of water to help it melt). A friend (many years ago, - 1970s?) made me a new exhaust pipe for the bike, and had an hydraulic bender, and used a proprietary "Brown melting gunge" that cooked in a saucepan, and being brittle when cold, it broke-up during bending the thin walled stainless tube (~2" dia) and the dust and broken shrapnel fell out after bending. - Maybe that was caramel? - he blocked one end of the straight pipe just by sticking it in the lawn for an inch, while we poured the gunge into it. After cooling, the whole thing was solid, and the tube bent like in a factory. Slight necking, and surface marks from the dies/rolls in the Hydraulic bender. 
But for your job, I think the (external) spring has given excellent results! - better than mine (I have tried the spring inside a tube - not easy to extract after bending!), I must try an external spring next time.
My benders: (The best for 3/16" or 5mm tube is the one next to the springs: Also, note the thick bar instead of flimsy steel strip for the black benders. Makes them much better.).




Thanks,
K2


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## Brian Rupnow (Aug 6, 2022)

Starting to run out of things to make--and that's a good thing. This afternoon I made the main brass turning for the intake manifold---in fact, I made it twice. First try was with some of the mystery metal I bought last week. As I was turning it, I realized that it was bronze, not brass. I don't even know if you can silver solder bronze, but I was willing to try. Then I found that I had misread my own drawing and I had one of the turned down areas too long. At that point I thru it in the can and started over with something I knew was brass.


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## Steamchick (Aug 6, 2022)

Excellent work Brian. To reply to your question... Yes, you can silver solder phosphor bronze. Also, aluminium bronze, although very difficult and needs special flux... I think? Phosphor bronze bushes are commonly silver soldered into copper boilers, threaded for fittings, because brass will de-zincify with the steam and temperature, so must not be used in boilermaking. Similarly, aluminium bronze can lose aluminium with a steam environment, so not recommended.
Just FYI. 
K2


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## Ghosty (Aug 6, 2022)

Brian,
You were thinking about the grand kids when you designed the micky mouse ears(gear cover), it does look good and cleans up the gear set quite well. It is one area that lets down a lot of great looking engines. Keep up the great work, Still following along.
Cheers
Andrew


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## Brian Rupnow (Aug 6, 2022)

Andrew and Steamchick--I'm glad that you are following my build thread and commenting. I have built at least one part per day since starting this build thread, and the end is somewhat in sight. I am getting to the point where I have to actually search a bit to find parts I need to complete this engine.----Brian


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## Brian Rupnow (Aug 7, 2022)

Todays offering to the Machine Gods is a cooling fan.  The discoloration is from the heat of silver soldering. I wish I had a small sandblaster, but I don't. This fan has been pickled in Citric acid, scrubbed with an old toothbrush and polished a bit with silver polish on a Q-tip. I may just pint it flat black.


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## Brian Rupnow (Aug 8, 2022)

This morning I made up the flanges which bolt the intake manifold/fan to the cylinder heads. It went well, so I figured a "mock up" shot was called for. Nothing is soldered yet, it's just held up there by the grace of God and tight tolerances. I still have to do some cosmetic work on the fan blade, but it is getting exciting.


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## Brian Rupnow (Aug 8, 2022)

This afternoon I cut the keyway into the crankshaft and into the starter hub. The flywheel had been keyed back when I first built it. I made a gasket for the inspection hatch in the bottom of the crankcase, filled it with #30 motor oil until oil began running out the overflow pipe, signaling that the crankcase had the correct amount of oil for splash lubrication. A few squirts of oil down the sparkplug holes, and then I drove my engine with an electric motor for one hour. This loosened everything up, and the motor can be easily spun over by hand now. Tomorrow I will solder the intake assembly and flanges together. I have to remake the axles that the hardened rocker arm ends mount on because of some minor clearance issues, and then all that is left are the exhaust tubes and the cams. I leave the cams for last, because they are always the parts I find hardest to make.


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## Steamchick (Aug 9, 2022)

Excellent work Brian. I too am excited - miles better than following the news, or rubbish on TV!
K2


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## Brian Rupnow (Aug 9, 2022)

Today seen the soldering of the intake manifold and the changes made to the small axles that hold the hardened part to the end of the rocker arms. I'm reasonably happy with this, and tomorrow I will make the exhaust pipes. I built an aluminum jig with the same bolt pattern as the two cylinder heads, and did my soldering on the intake out in the main garage away from the engine.


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## stevehuckss396 (Aug 9, 2022)

Sounds like your really getting close. Has to be a very short punch list. Looking forward to her first pops.


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## Brian Rupnow (Aug 9, 2022)

We're getting right down to the last strokes Steve. I'm agonizing about the exhausts right now. The exhausts are close to the gas tank, and I don't want the first run to be the last run. I would stick with my original exhaust design but there is really no good way to put such tight 90 degree bends into 3/8" o.d. tubing.


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## stevehuckss396 (Aug 9, 2022)

Could a standard brass fitting from the hardware store be machined to accept your tubing? Something like this with the barbs cut off and reamed so your tubing slips into it.


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## Brian Rupnow (Aug 9, 2022)

I think I've designed something that will work. My exhaust ports are threaded 5/16"-18, so there isn't any good way to make sure that the exhaust tube tightens into the thread at the exact moment that the 90 degree section is aimed in the correct direction. My design isn't quite as pretty as a flowing 90 degree bend, but it addresses the problem.


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## stevehuckss396 (Aug 9, 2022)

Awesome,  can't wait to see what you have come up with


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## Badhippie (Aug 10, 2022)

Brian 
That girl looks great I really like the design. I can not wait to hear it run. Looks like she is not far from it either


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## Brian Rupnow (Aug 10, 2022)

This is my current exhaust system plan. My cylinder exhaust ports have a 5/16"-18 internal thread.


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## Brian Rupnow (Aug 10, 2022)

Exhaust Details


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## Brian Rupnow (Aug 10, 2022)

I'm very happy with the way this turned out. I especially like that I can adjust the angle of the exhaust pipes to be any place I want it. If I want to remove the exhausts, I can heat the "cap" with my torch to allow me to remove it and access the bolt which holds the exhaust to the cylinder head.


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## Brian Rupnow (Aug 10, 2022)

I think that just about covers everything except the cams which operate the valves and the pushrods. I still lack one bearing for the fan, but it is supposed to be here this week. I may discover the odd thing here or there as I go to finish everything up, but by and large, the heavy duty machining and fabrication is finished. I started this build on the 15th of June, and by the 15th of August the cams should be finished. I have worked on this engine every day since I started building it.


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## Badhippie (Aug 11, 2022)

Brian
It looks great that was a good work up of the exhaust. Sounds like we may see a running engine in a few weeks 
Tom


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## awake (Aug 11, 2022)

Brian, I love the look of the exhausts. I am curious about two things: 1) will this design cause undue back pressure on the exhaust (constriction, sharp 90° turn), and 2) how would one tell if that were the case??


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## Brian Rupnow (Aug 11, 2022)

Awake---the sharp 90 degree corner will have some effect, although it may not be measurable. The only way to tell if your exhaust  system is causing too much backpresure is that eventually your exhaust valves will burn out.


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## awake (Aug 11, 2022)

Ah, interesting. I hadn't thought about the effect on the exhaust valves. Thanks for the response - I know just enough to know that I don't know very much at all about the ins and outs of engines, model or otherwise.

Of course, no more than I tend to run a model engine, it might take 100 years to make a difference ...


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## Brian Rupnow (Aug 11, 2022)

HELP!!!  I know that there are two main methods of cutting cams for these small i.c. engines. One method uses a vertical milling machine and a printed out set of offsets that will give you the cam profile that you want if followed precisely. I have used that method in the past, but windows 11 seems to not run the charts I originally used. The other method also uses the vertical milling machine and after initial set up there are no charts used in machining the cam. I THINK someone has set up these offset charts for the first method on an excel spreadsheet. I would like to use the first method with the excel spreadsheets, because it lets me cut all four cams at once. Can someone please point me to a post where I can download and use these excel spreadsheets, and perhaps a post where it all gets explained. It has been a long time since I used that method of cutting cams.---Brian


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## Mike1 (Aug 11, 2022)

Brian Rupnow said:


> HELP!!!  I know that there are two main methods of cutting cams for these small i.c. engines. One method uses a vertical milling machine and a printed out set of offsets that will give you the cam profile that you want if followed precisely. I have used that method in the past, but windows 11 seems to not run the charts I originally used. The other method also uses the vertical milling machine and after initial set up there are no charts used in machining the cam. I THINK someone has set up these offset charts for the first method on an excel spreadsheet. I would like to use the first method with the excel spreadsheets, because it lets me cut all four cams at once. Can someone please point me to a post where I can download and use these excel spreadsheets, and perhaps a post where it all gets explained. It has been a long time since I used that method of cutting cams.---Brian


Brian, Is this the post you have in mind *Link* CamCalc - Manual Numerical Control | Model Engineer Click on the link within the post

Mike.


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## stevehuckss396 (Aug 11, 2022)

Sorry I can't help Brian. I use the 3rd method which uses the lathe.


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## Brian Rupnow (Aug 11, 2022)

Thanks Mike-1  I will have a closer look at that tomorrow, but it looks like what I am after.---Brian


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## Brian Rupnow (Aug 11, 2022)

I did surprisingly little today, and Damn, it felt good!!! I did complete the assembly of the fan, fan shaft, two roller bearings and a bearing spacer. After it was finished I painted the fan and fan pulley with a couple of coats of flat black enamel. It is still quite "fresh" in this picture---it will get flatter as a bit of time passes. I will assemble it with the rest of the intake manifold tomorrow. I did get a response to my request for a post about the cam-calc method of machining cams, and will take a deeper look into it tomorrow.---Brian


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## Gordon (Aug 12, 2022)

When making a cam how important is it to have a radius on the flank? There is only a few thousands of lift and the action actually takes place at the nose. As long as the valve opens and closes at the proper time how does a gentler action make it any better. We are talking about engines run at low speeds and for limited time. If the cam or cam follower wore out after 5000 hours none of us would ever see it. I have made cams successfully with a straight flank as shown on several plans that I have followed.


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## Brian Rupnow (Aug 12, 2022)

General theory is that if the cam has a flat flank, then the flat flank rotates around and "slaps" the bottom of the lifter each time the cam rotates. This supposedly causes early failure of the valve train because of the vibrations caused by these repeated "slaps". Is it a real concern? I don't really know. Apparently cams with flat flanks should only be used with roller cams that have  a wheel attached to the portion that comes in contact with the cam.


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## stevehuckss396 (Aug 12, 2022)

The flank radius does a few things. One it helps to accelerate the opening of the valve in a controlled way. It's kind of like pushing the valve open unlike a flat flank is more like hitting a baseball with a bat. That's a gross exaggeration but kind of gives you the general idea.

The flank radius also has an effect on how big or small the bottom of the lifter has to be. If the bottom of the lifter is too small the bottom edge will dig into the flank as the lobe comes up to the top and then skid down the other side of the flank. I have seen some people get around it by putting a large radius to putting a ball end on the bottom of the lifter. Eliminates one problem but now the only contact between the lobe and lifter is a small contact patch dead center of both parts. At the scale we build them with the couple pound springs and the infrequent running of the engines I doubt either would wear our in our lifetime. A flanked radius with a large enough lifter and there will be a contact patch as wide as the lobe giving a far better design.


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## Brian Rupnow (Aug 12, 2022)

Today, I'm making cams. Unfortunately, I was not able to use the cam-calc tables that people so kindly sent to me. It could be that my software won't run it, but it is also possible that since I have very little knowledge of Excell spreadsheets  I didn't know how to operate it properly. That's okay, my method yields a perfect cam with radiused flanks. There are no mathematical tables to use, but my right arm may fall off from taking the 90 plunge cuts required to do this right. I am going to start another thread on machining the cams, but for now, this is the cam that my method yields.


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## Gordon (Aug 12, 2022)

Thanks Steve. That is pretty much what I thought but as you also said when we are talking about low RPM, low power and low usage engines it seems like a lot of work for not a great deal of advantage. Some folks here are building high speed engines so that flank radius may be more important but most of us are trying to run our engines as slow as possible and a run of 15 minutes is a long run. If you are designing automobile engines to run at high speeds for 100,000 miles you are in a different situation.


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## Brian Rupnow (Aug 12, 2022)

So there we have it. Four little cams with curved flanks, all in a row. And really, I've been about 5 hours getting to this point. They are all made from 01 steel, and will all be flame hardened and quenched.  Before I harden them, I have to drill and tap them for set screws. That 5 hours includes turning  a piece of 3/4" 01 steel down to 0.640" diameter, sawing off four lengths about 1 1/4" long with my bandsaw, squaring the ends of each piece in the lathe, and drilling/reaming each of the four pieces to 5/16" diameter. They're not exactly the same, but they were all done on manual machines.


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## stevehuckss396 (Aug 12, 2022)

Yes Gordon, very true on all accounts. One thing I didn't mention was longevity also depends on your choice of material.  If you run a flank radius not a big deal but options b and c with the modified lifter bottoms it's important. Brian chose O1 tool steel for a cam shaft. Very good choice even if he didn't harden it. I also make my lifters out of 12L14 leaded steel. The lifters are softer than the cam so they wear faster. Easier to make than a new cam. With that combination, as long as they get a little oil splashed on them, they will out live both of us.


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## Brian Rupnow (Aug 12, 2022)

Steve--I do flame harden and oil quench the cams and the lifters. That's why I make them from 01, so I can harden them.---I just did that to the cams I made earlier today.---Brian


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## stevehuckss396 (Aug 12, 2022)

They will out last your grand kids with proper lube. Nice job sir!


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## Steamchick (Aug 13, 2022)

Mentioned above was the 100.000miles for car engines. Multiply that by between 2 and 5. to 200,000~500,000miles. The durability tests for cams and followers in an engine were done at idle (Muggins being the engineer to specify the test and test rig). Idle (in the profiles and contact loads for regular car engines) is the hardest speed for durability, as the oil supply is adequate - but contact pressures at their highest due to dynamic acceleration and deceleration forces not having much effect: 
The Cam profile on a flat follower (OHC twin-cam with bucket follower designs) leads to gentle opening then to an acceleration peak which "flings" the valve open at higher speeds, allowing the spring pressure (increasing with valve opening) to absorb that kinetic energy of valve motion so at Peak revs the system will happily run "forever".. But at idle the mechanics have to be "dragged up the hill" of the cam and "drag all the way down again". This "dragging" wipes the surfaces of oil as the contact "sees" full spring load all the way up and down the cam,  hence hardest for durability - and the tests ran for the time equivalent to 200,000 miles of "normal" driving. It may sound extreme, but the design and parts eliminated warranty concerns for cam wear.
I guess Brian's parts will be as good!
K2


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## Brian Rupnow (Aug 13, 2022)

Machining and fabrication is complete. This video shows operation of the cams, push-rods, and rocker arms. Next step will be to see if I can persuade this engine to run.


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## stevehuckss396 (Aug 13, 2022)

Sounds like you got the easy part done. Now the real work begins. At least that's how it seems sometimes.


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## Brian Rupnow (Aug 13, 2022)

Steve---I totally agree with you. The machining and assembly is the easy part.----Brian


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## Bentwings (Aug 13, 2022)

Gordon said:


> When making a cam how important is it to have a radius on the flank? There is only a few thousands of lift and the action actually takes place at the nose. As long as the valve opens and closes at the proper time how does a gentler action make it any better. We are talking about engines run at low speeds and for limited time. If the cam or cam follower wore out after 5000 hours none of us would ever see it. I have made cams successfully with a straight flank as shown on several plans that I have followed.


Little un clear on question, if you men flat relative to the axis you are probably right . Unless there is large valve spring pressure and you don’t have a good splash lubrication , you will wear out long before the little engine. A radius profile is to promote lifter rotation  a straight profile might be better for roller lifters. I’ve got a number of two stroke engines that have hundreds of hours at full throttle full load maximum rpm , often operating far above normal temps  that still run just fine and have the same compression as new  most four stroke Rc guys say the same thing just use quality oil  and compatible cam and lifter materials auto enginges usually have cast or sintered cams that are relatively hard good finish, lifter are chilled iron and basically quite hard  I never wore a race cam out , a couple broken rollers  wiped out roller cans but 600+ Pounds  on the valve seats was not unusual Hogson radial engines show plastic lifters  cams are very gentle .


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## stevehuckss396 (Aug 13, 2022)

The two hodgson engines I am working on have lifters made of drill rod. I hope you haven't made yours in plastic.


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## Claudio Masetto (Aug 14, 2022)

I have never heard of anyone on this forum using Teflon to make cam followers. I have used it on this small engine and they perform great as they are self lubricating.


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## Steamchick (Aug 14, 2022)

Hi Brian, Just something I am not sure about from your video? It Looked like the cam timing was Inlet (nearest to the flywheel you are rotating) opened-closed - and immediately the exhaust opened-closed. - Then a dwell... for compression and firing. Surely this sequence is wrong and the normal rotation of the engine would be the reverse direction? Of course it doesn't matter while demonstrating the action for valve gear, but will be important for the starting of the engine, and perhaps the quick release connector on the end of the flywheel? 
I guess you have not got your directions of cams "muxed-ip" and will be running counter-clockwise at the flywheel?
Or am I muxed-ip?
K2


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## Brian Rupnow (Aug 14, 2022)

Watch the video again. listen to the part where I say that I haven't timed the engine yet.---Brian


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## Brian Rupnow (Aug 15, 2022)

Today I assembled the cams for the other cylinder and made up a pair of pushrods. The rockers now operate on both sides when I turn the engine over. I went across town to Hercules O-ring and begged a couple of 1" i.d. Viton o-rings to use for my head gaskets. This is getting harder and harder to do---I used to know all of the Management there, and they gladly gave me whatever Viton rings I needed in exchange for $5 for their coffee fund. The management is all new there now, and they don't know me.  I find it difficult to order Viton o-rings in the sizes I need unless I want to buy a thousand of them. I leak tested my gas tank by filling it full of Naptha gas and setting the engine on a piece of white paper overnight. The paper had no tell tale stains on it in the morning, and the fuel level stayed the same in the tank overnight. I have to make up gaskets for the bottom of the cylinders where they attach to the crankcase.---There is no compression there, but the engine has an oil base and splash lubrication, and if I don't put gaskets there it will leak oil.


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## Brian Rupnow (Aug 16, 2022)

Today was the day to start thinking about piston rings. I have a number of heat treated rings which were originally made when I built my 7/8" bore horizontal i.c. engine. Whenever I set up to make piston rings, I make a bunch of extras, and they do get used up. These pistons are prototypes. They are made of cast iron, and the top two ring grooves get the heat treated cast iron rings. The third groove down from the top of the piston get a single Viton o-ring. (Which you can see on the left side of the picture). Theory here is that the Viton rings will give immediate good compression to start the engine. After the engine has started on it's own and ran for an hour, the cast iron rings will "wear in" to the cylinder to provide compression. The rings in the picture haven't been ground for flatness nor "fit" to the pistons, that will be done tomorrow.


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## Steamchick (Aug 17, 2022)

Clever thinking Brian. I hope it works. My only concern is that the Viton ring may wipe the oil from the bore so effectively that the cast iron rings have insufficient lube to avoid scuffing/seizing...? But you will only find that out if things go wrong. I am sure your initial runs will be  short, low powered, and you'll check to see how the rings are bedding-in... so you should be OK. Even so, I should be inclined to add the finest smear of molybdenum grease to the bore during assembly, as while this may slow the bedding-in process, it should also prevent any scuffing/damage to rings and bore. But a tiny amount on a finger should do..? 
Only a thought, your thoughts (and experience) are probably better?
K2


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## Steamchick (Aug 17, 2022)

Just another thought... along he lines of an Engineer fitting parts... Have you considered using engineers' blue on the bore, fit the rings to a piston and pass it up and down the bore, then see where the blue transfers - or not? 
Or:
I should be tempted to even just simply try the cast iron rings on the pistons and run (with cylinder heads and valve gear to gain compression in the cylinders) for 5 mins or so driven by your trusty electric motor. (no fuel or ignition). Then check the rings have a witness polish all around, and some compression is evident, before trying to run on fuel?
Or have you already checked?
K2


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## Steamchick (Aug 17, 2022)

Hi Claudio, When I worked on compressed air powered cylinders, we had PTFE seals, working on rotating or linear action ground stainless steel shafts. - Lubricated with a silicon grease. (NOT the regular mineral oil LM grease or anything like it - that absorbs moisture and forms acids...).  I suspect silicon grease may help the "self-lubrication" of the PFTE? It was a requirement for the 40 years maintenance free life of my product (max. 5000 cycles).


			https://cpc.farnell.com/pro-power/ppc114/grease-silicone-100g-tube/dp/SA03684?mckv=EaYVqgXR_dc|pcrid|74354493099737|kword||match||plid||slid||pid|SA03684|&CMP=KNC-MUK-CPC-SHOPPING&s_kwcid=AL!8472!10!74354493099737!4577954105008945&msclkid=e7d0d294b7ae1b2f58f8b0682d80924d&utm_source=bing&utm_medium=cpc&utm_campaign=M-790-Shopping-Tools%20and%20Maintenance&utm_term=4577954105008945&utm_content=Cleaning%20%26%20Chemicals
		


K2


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## weldme (Aug 17, 2022)

Steamchick said:


> Hi Claudio, When I worked on compressed air powered cylinders, we had PTFE seals, working on rotating or linear action ground stainless steel shafts. - Lubricated with a silicon grease. (NOT the regular mineral oil LM grease or anything like it - that absorbs moisture and forms acids...).  I suspect silicon grease may help the "self-lubrication" of the PFTE? It was a requirement for the 40 years maintenance free life of my product (max. 5000 cycles).
> 
> 
> https://cpc.farnell.com/pro-power/ppc114/grease-silicone-100g-tube/dp/SA03684?mckv=EaYVqgXR_dc|pcrid|74354493099737|kword||match||plid||slid||pid|SA03684|&CMP=KNC-MUK-CPC-SHOPPING&s_kwcid=AL!8472!10!74354493099737!4577954105008945&msclkid=e7d0d294b7ae1b2f58f8b0682d80924d&utm_source=bing&utm_medium=cpc&utm_campaign=M-790-Shopping-Tools%20and%20Maintenance&utm_term=4577954105008945&utm_content=Cleaning%20%26%20Chemicals
> ...


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## Brian Rupnow (Aug 17, 2022)

Today the cast iron rings were finished "to size" and installed on the pistons. The Viton ring was added to the pistons as well. Using a tapered ring compressor, the pistons were installed into the cylinders. Ended up being a very tight fit, but they are in, the cylinder walls didn't get scored in the process, and I'm happy with the fit. In this picture, the pistons have been shoved thru the cylinders until the piston pin hole is just visible, enough to get the piston pins started into place. The rings are all still compressed in the cylinders. One of the things about a small bore engine using knife and fork connecting rods is that the connecting rods  (at least the forked one) won't fit thru the hole in the cylinder. This means that the piston pin must be installed thru the piston and rod while the rods are still attached to the crankshaft.


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## Steamchick (Aug 17, 2022)

Lovely! I am sure it will run soon!
K2


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## SteamChEng (Aug 18, 2022)

Great stuff!  I'm really looking forward to seeing this run!

Any further thoughts on making a "second half" to make it a V-4?

-Dave


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## Brian Rupnow (Aug 18, 2022)

The pistons with rings are installed in the engine. It is very, very stiff. It is too stiff to consider running on it's own. I used a cheater bar to turn the crankshaft thru 360 degrees, and when I was sure there were no definite "Hardstops" in the engine, I turned it over 200 times by hand. This freed things up to the point where the engine would turn over, but still stiffer than Hell. I filled the crankcase with oil, gave a shot of oil down each cylinder (the heads are not on the cylinders). I put my 8" v-belt pulley on the crankshaft and my two inch v-belt pulley on the electric motor I have, connected them up with a v-belt, and set it up to run for a half hour out in my main garage. I don't have any work planned for the rest of the day, as I'm off to see my friendly neighborhood dentist this afternoon.


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## Brian Rupnow (Aug 19, 2022)

So--we are almost ready to rock and roll!!! Head gaskets are in, rings are in, everything that bolts together is bolted together (except the gear guard) which will be installed after the engine has been ran. I have to set the valve and ignition timing before I attempt to start the engine, and do a bit of electronic rigging for the ignition. Wish me luck peoples.-----Brian


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## stevehuckss396 (Aug 19, 2022)

Best of luck brian!


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## Basil (Aug 19, 2022)

Looking forward to seeing it run Brian


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## Steamchick (Aug 20, 2022)

Ok, if you need luck - GOOD LUCK!
But I think your expertise is sufficient!
K2


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## Brian Rupnow (Aug 20, 2022)

So, what did I do today on the engine?---Not much that shows, really. I cobbled together a wooden base that would hold one of my cylinders truly vertical. Setting up the valve timing is a lot easier if I start with a cylinder that is truly vertical, rather than laid over twenty five degrees.  Of course, before you can set the valve timing, you have to set the correct valve lash. This took me down the road of having to finalize my valve lash adjusting screws and soldering the knurled tops onto the #5 bolts---and putting c-washers on the rocker shafts and on the shafts for the hardened donut that fits on the end of the rocker arms.---In the middle of all that a man with an idea for a new invention showed up at my place and we discussed that for two hours.---Then I had to mow the lawn, whipper snip the weeds, and blow all the cut grass off my Unistone driveway so it wouldn't start sprouting grass all over the driveway. Then I got an email from someone I had sold a set of drawings to for my 7/8" bore horizontal engine, saying that a bunch of drawings were missing from the package I sent him. I went thru all the files on that engine and he was right, I had to chase down about 20 drawings, save them as pdf files and send them to him. It was an interesting day!!!


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## Steamchick (Aug 21, 2022)

Hi Brian. I like the simple solutions to make the calculations "more direct". I would have just fiddled on adding and subtracting the 25degrees here and there - maybe including errors!
And now you also have the front slope for a car wheel-ramp to add to your collection.

K2


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## Brian Rupnow (Aug 21, 2022)

So---we're all ready to set valve timing. Piston is at top dead center, timing pointer is pointed straight up at "0" degrees (you can just see the tip of it sticking up past the degree dial.) Enough of the starter hub is exposed to let me turn the crankshaft to move the timing pointer. Both intake and exhaust cams are exposed thru the side of the camshaft support block to let me rotate the cams into the correct position. Now I have to go and help my good wife get set up for a family birthday party!!


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## Gordon (Aug 21, 2022)

Maybe I am missing something here but why tilt the engine instead of just rotating the degree wheel by 25°?


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## Brian Rupnow (Aug 21, 2022)

Because I'm old.--EDIT--EDIT--Sorry Gordon, that was a bad answer. it's just that I always find this timing procedure somewhat complicated, and the fewer numbers I have to juggle, the better I like it.----Brian


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## Brian Rupnow (Aug 22, 2022)

Okay, it's time to rock!! Valve timing is set. Ignition timing is set. Gas line is hooked up. Gas tank has been leaktested. Electrical connection to the  the points are ready. My "coil box" that I use to run all my single cylinder engines will do for one set of points. I have a spare ignition coil and switch, so tomorrow I will have to cobble up a second "coil box" to run the other set of ignition points.


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## stevehuckss396 (Aug 22, 2022)




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## rick9345 (Aug 22, 2022)

)long time lurker, and an old guy self taught machinist,(79) BIG THUMB *UP*!!


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## Brian Rupnow (Aug 23, 2022)

Progress is slow. In order to give a second ignition system for the second set of points on this engine, I have to have a second coil, switch, and on/off light. I've had a 12 volt coil hanging on the wall since 2013 with a note on it "Coil may be bad". I'm going to assume that the coil is good, and having dug around in my cupboards I've found a switch and an on/off indicator. This second ignition source will be nowhere near as sophisticated as my original "coil box" but it should get the job done.


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## Badhippie (Aug 23, 2022)

Brian 
She looks like it’s ready run very nice build 
 Good luck 
Tom


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## Gordon (Aug 24, 2022)

I am not sure about this design and I may be completely wrong. I was wondering if you could use your dual snowmobile coil but then I realized that the two cylinders are not at 90° to each other so they are not firing in a true four cycle sequence. Aren't the cylinders fighting each other for part of the cycle since they are both on the same crank throw? On most multi cylinder engines the crank throw is offset so the cylinders are not fighting each other. I am trying to wrap my head around this and as I said I may be completely wrong.


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## Steamchick (Aug 24, 2022)

Hi Gordon, while I do not really understand these things, I have heard of twins at 360 degrees, 180 degrees, 75 degrees, 45 degrees, 60 degrees, 90 degrees, and someat weird numbers, all to do with variations on balance factors. Brian uses 50 degrees. He can explain that one. But racing bike multi-cyinder engines sometimes have 2 cylinders firing together,  for a big- bang effect which gives the rider more feel for the rear wheel grip when cornering!
The v-twin makers either do it for packaging, or for balance, when the axial imbalance of one cylinder can be off-set against the transverse imbalance of con-rod etc. waggling sideways back and fro....
I have a book on steam loco design where balance of engines, rods, wheels all combine and the same equations can be used on infernal combustion engines.... or a bit of fiddling with a stick-on weight or 2 on the flywheel!
So all things are possible?
Does that help?
K2


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## Steamchick (Aug 24, 2022)

Hi Gordon, pardon me, I was thinking of engine dynamic balance.
We're you querying the firing?
On a simple 50 degree Vee, the firing would be 1 fire + (360 + 50) = 410 degrees to fire 2, then (360-50) =310 degrees to the no 1 next firing. So not a problem? Even more off-beat on Vee-twins with up to 90 degree Vee.
Is that a help?
Or have I still missed your point?
K2


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## Gordon (Aug 24, 2022)

Steamchick said:


> Hi Gordon, pardon me, I was thinking of engine dynamic balance.
> We're you querying the firing?
> On a simple 50 degree Vee, the firing would be 1 fire + (360 + 50) = 410 degrees to fire 2, then (360-50) =310 degrees to the no 1 next firing. So not a problem? Even more off-beat on Vee-twins with up to 90 degree Vee.
> Is that a help?
> ...


I am wondering about firing. It would seem like one cylinder would be in part of the stroke ,starting compression for instance while the other cylinder would be in another part of the cycle, finishing power for instance and the two cylinder are fighting each other. 90° means that they are on opposite ends of the cycles. In a multi cylinder engine this can be avoided by offsetting the crank throw. I am not at all sure about this but most "V" engines seem to have 90° offset or a crank with the proper offset for the two cylinders so that the pistons are on opposite ends of the cycle. I probably am not expressing this well.


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## Brian Rupnow (Aug 24, 2022)

As best I can explain this.--Engine rotation is clockwise when viewed from flywheel side. First piston comes up on compression stroke and fires. At the same time, second piston is coming up on exhaust stroke. First piston fires, and 50 degrees later the second piston reaches TDC and starts down on it's intake stroke. This gives the engine a noticeable "lope" when it is idling, but smooths out as engine speeds up.


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## Gordon (Aug 24, 2022)

I built the Jerry Howell "V Twin" and this is what he said:

This is a V-Twin engine that is machined entirely from bar stock. It has no prototype as it is entirely my own design. Being a single crank pin 90 degree engine, it is extremely smooth and vibration free. V type engines other than 90 degree can not be balanced except with special balancer shafts, etc. that you wouldn't want! Witness the vibrating 45 degree motorcycle engines​
Perhaps the problem is balance more than ignition


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## Jasonb (Aug 24, 2022)

The two conrods on a common crankpin seems to work OK for Harley Davidson so I'm sure Brian's will too. It's not a lot different in general layout to the Hoglet model engine and they run OK too.


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## Brian Rupnow (Aug 24, 2022)

I'm about to try and start the engine, but I have discovered that the coil hanging on the wall really was bad.----Poop!!! Should have threw it away 10 years ago. I just called PartSource and a new 12 volt coil is $60. I'm trying to reach Canadian Tire to see if they have any cheaper coils. While I wait for Canadian Tire to call me back about a coil, I'm sorting out my shop and putting away tools and cleaning machines.


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## werowance (Aug 24, 2022)

not sure if you have a tractor supply in Canada or not (or even near by) but they used to have very cheap 12 and 6 volt coils for old tractors.  i picked up my coil for my old farmall there years ago seems like about 25.00.  but who knows if inflation and such what they sell for there now days.

edit - they were generic brand for points ignition.


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## Steamchick (Aug 24, 2022)

A second-hand motorcycle coil should be considered. 
Gordon, is the snowmobile engine a 90 degree Vee?
I have an idea that a coil that fires through 2 leads simultaneously (redundant  spark) should work, but I haven't yet sat at the board and drawn the cycles to see where the redundant sparks fire.
Is that what the snowmobile  coil does?
K2


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## Gordon (Aug 24, 2022)

Steamchick said:


> A second-hand motorcycle coil should be considered.
> Gordon, is the snowmobile engine a 90 degree Vee?
> I have an idea that a coil that fires through 2 leads simultaneously (redundant  spark) should work, but I haven't yet sat at the board and drawn the cycles to see where the redundant sparks fire.
> Is that what the snowmobile  coil does?
> K2


I don't know. Brian has the snowmobile coil that he used on another twin. Apparently the two cylinders are 40° out of sync so I am not sure how that would work out. I think that it would fire at TDC (0°) then 40° and then again at TDC


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## Brian Rupnow (Aug 24, 2022)

Exciting time at the Rupnow house!!! I bought a new coil, wired everything up, and the engine is firing dependably on one cylinder. The second cylinder is firing sometimes. Engine hasn't decided to take off and run on it's own yet, but damn, it's close. I've developed a massive oil leak, and initial impression is that it's coming from that access door I cut into the bottom of the crankcase to  get at the rod bolts. I will dump the fuel back into it's regular container, turn the engine upside down, and have a look at the oil leak---Got to fix that, because once the engine runs on it's own I don't want to shut it off for half an hour.


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## Steamchick (Aug 24, 2022)

Hi Gordon, I don't  think it is 40 degrees, but a whole revolution and 40 degrees. Which would be an inlet stroke at a pressure too low to ignite.
That's basically how my Moto  Guzzi  runs... no problem.
K2


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## stevehuckss396 (Aug 24, 2022)

Well shoot Brian I was really hoping today would be the day. Sounds promising!


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## Brian Rupnow (Aug 24, 2022)

Today the first change has been made. My beautiful exhaust pipe assemblies were just the right length to dribble oil out directly onto one set of ignition points. This was not good, so I have added 1 1/4" extensions to my exhaust tubes. I have changed the solid model, and drawing to show the pipes at the correct length.


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## Steamchick (Aug 25, 2022)

Brian, here are UK coil prices.
Car coil £30. Motorcycle (smaller) coil £28...
Twin plug (single coil redundant spark, not so suitable for your separate contact breakers) £70.
CD ignition kit: 5-piece Set of DC CDI with Wire & 12V Rectifier & Relay & Ignition Coil with Spark Plug Cap Fits for Irbis ATV 150U
Any use?
Probably the post and import duty make local stuff cheaper for you?
K2


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## Brian Rupnow (Aug 25, 2022)

30 Pounds are 45 Canadian dollars. It isn't cheap being a Canadian. My coil was $60 plus tax, ended up being $67.30. I might have found a cheaper source at a farm and tractor supply company.


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## Gordon (Aug 25, 2022)

I have been using the COP (coil over plug) coils as used on Ford and a few other cars. You can buy a set of 8 from eBay for $25/$30. Another option is to get them from the junk yard. They are small and seem to work just fine.


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## Steamchick (Aug 25, 2022)

£100 each in the UK (New), so even junk yard COPs are not cheap.
K2


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## Gordon (Aug 25, 2022)

Steamchick said:


> £100 each in the UK (New), so even junk yard COPs are not cheap.
> K2


A set of eight for a Ford eBay US as low as $32
Set of four for Mazda eBay UK £14.95

Both sites also list them for 8 to 10 times that for one but there are several other options for Mini Cooper BMW Peugeot.

These may not be the greatest quality but for this purpose they should be adequate.


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## Brian Rupnow (Aug 25, 2022)

Gordon--thank you for that info. if I need any more coils I may use that approach. Today the engine ran. Both cylinders fired quite well. Had a two minute sustained run. I have way, way, way more oil than the engine can cope with.--Engine could be used as a mosquito fogger. Blue smoke like you wouldn't believe coming from both exhaust pipes as it ran. Okay--I'm pleased as punch!!! At the end of the two minute run, both sparkplugs were overwhelmed by oil and the engine slowed down and quit. Now I have to make a decision about my oil in the engine. One of the possible solutions is to cut access holes in the engine endplate where the ignition points are located. I could reach in with my trusty oil squirt can and lube the big ends of the connecting rods.----forget about having an oil sump. The only problem with that is how to get oil to the small end of the con rods, up inside the piston. Anyways, I'm happy happy happy. Videos will follow once I get the oil situation figured out.


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## Ghosty (Aug 25, 2022)

Brian,
Do you have a crankcase vent? You never mentioned it in the build. It could be causing the oil problems as the crankcase has to vent somewhere.
Cheers
Andrew


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## Brian Rupnow (Aug 25, 2022)

No Andrew, I don't have a crankcase vent. I will think on that.-I'd like to keep the oil base.---Brian


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## stevehuckss396 (Aug 25, 2022)

You might just be over full and slinging way more oil up than the rings an o ring can scrape off. Try lowering the oil level a bit and see what happens.


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## Ghosty (Aug 25, 2022)

Brian, 
That would do it, as the pressure in the crankcase builds up, it pushes the oil out every where, in cars it is usually any gasket, rocker cover usually. Shown in the pics is a Saito FG-17 running on 20-1 petrol/oil mix, as can be seen is the amount of oil being pushed out the crankcase vent.
Cheers
Andrew


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## Brian Rupnow (Aug 25, 2022)

I checked on my CAD software, and I can lower the oil level 0.2" and still touch it with the rotating conrod. I will do that tomorrow and then have a test run.  If it still oil fouls the sparkplugs I will open up the engine endplate for oil squirt oiling.


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## payner (Aug 26, 2022)

Brian. Great to hear you got it running .
That pressure building up in the crankcase may be why you are getting so much blue smoke out the exhaust ( oil vapour forced by the rings ) and the pressure will cause extra leakage at your access cover in the bottom .
I'm not sure what RC 4 stroke model engines use , the smallest I've seen is a Honda 4 stroke trimmer .
You may be able to incorporate it into the plug of your oil fill assembly .
Bill


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## werowance (Aug 26, 2022)

Brian, on the Crank Case Vent suggestion,  do you think maybe remove the pipe plug in the oil filler elbow and maybe take an old grease rag or something over it with a rubber band to keep it covering the hole just for a test?  sure without a grease rag or something it would likely blow oil out of that as well.  and maybe even with a grease rag.  but just curious.  i cant wait to see a video of it running.


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## Brian Rupnow (Aug 26, 2022)

The drain plug for engine oil has been moved down a good 1/4". The hole which originally had the oil drain pipe in it has been sealed with  a 1/2" threaded plug, and a new #10 hole has been drilled directly below it. I set the engine up in the run position and inserted a piece of 3/16" rod thru the hole horizontally. When I turned the engine over by hand, the 3/16" rod moved a bit, so I know that the con rod is still going to touch the pool of oil. Now, back to the bench for some more test running.


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## Brian Rupnow (Aug 26, 2022)

Even with a reduced amount of oil in the sump the oil is still splashing up onto the cylinder walls, getting past the rings, and overwhelming the sparkplug.  So----No oil sump. Now I will cut access holes in the engine backplate for squirt can oiling of the rods big ends.


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## SteamChEng (Aug 26, 2022)

Hot dawg!  That thing runs like a scalded cat!

Nice job, Brian!  I guess the "squirt oiling" method will work, but you can probably still lower the oil level a little bit more and still get it to splash just off the influence of parts flinging around in there.  Or you could add an oiler tube and have a cool little drip oiler off to one side somewhere.

Think you'll ever add a second half to make it a V-4?

Cheers!


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## mayhugh1 (Aug 27, 2022)

Brian,
In a multi-cylinder engine, you don't need (and in most cases don't want) to run a sump level where the crank throws, or even more likely the rod caps/bolt heads, are dipping into the oil. With the oil level sitting clear of the moving parts, the windage created by the crankcase pressure pulses will create an oil storm inside the crankcase that will keep its interior wet with oil. Even full-size engines with oil pumps use this windage to wet the cylinder walls. All the engines I've personally worked on have had windage trays to limit this oil storm and in the process free up a little horsepower. 

Fill your crankcase with oil so the level is just below any of the crank's moving parts. Then run the engine. Suck out oil as needed to reduce the oil smoke to an occasional puff at idle and somewhat more at w.o.t. This will be the level you want to run at and will ensure everything inside the crankcase is kept wet with oil and well lubed.

Your rubber o-ring isn't doing much to help with oil control and in fact may be worsening the problem by trapping oil between it and your bottom cast iron ring which would otherwise be trying to scrap the oil away during the piston downstroke. - Terry


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## Brian Rupnow (Aug 27, 2022)

Today, for the first time in 10 weeks, I haven't worked on the engine. I've spent the day cutting grass and catching up on all the other things I've let go over the summer. Tomorrow I have to go to my oldest son's house and put in a new sump pump line before the weather turns cold. I've had a couple of runs out of the engine, one which I videoed and a longer run that I didn't. I've learned a couple of things, which I will discuss later on as this thread continues. Thank you all for following my build thread, and yes, there will be more---just not right away.


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## Brian Rupnow (Aug 30, 2022)

Old bones are still in recovery mode from putting in a 100 foot sump pump line at my oldest sons place. He has early onset Parkinsons disease, and I try and help him out whenever I can.  I haven't went near the engine for three of four days, and I've enjoyed the break from it. Just for the record--I do take advise from people who post on my builds. Not all of the advice, not all of the time, but some of it. I know the engine runs, you've seen it in a video I posted. I want it to run slower and more dependably, so now that the pieces have all been machined and assembled I will devote some energy in tuning the engine. The fact that the engine runs gives me a pretty good feeling about the valve sealing.  For now, I am going to run with a dry sump and use "squirt can oiling" thru the holes I machined in the engine backplate. I think that I will remove the "knife" style con rod and cylinder and set the engine up to run the way I want as a one cylinder engine. When I am happy with that, I will reinstall the con rod and cylinder and then concentrate on running it with both cylinders installed.


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## NapierDeltic (Sep 6, 2022)

Hi Brian. First I have to say I follow closely this thread and I enjoy both your design solution and the build.
Looking at full sized engines ways of dealing with this (I'm speaking of the 3rd piston ring area), how  about making radial holes in piston and maybe in the cast iron ring combined with a middle groove - for excess oil drain? 
Assembling  refurbished motors I also know that even this might not be enough for a new pair of cylinder/ piston/ rings; of course, not speaking of other factors -already mentioned - which add to smoke in exhaust.


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## Brian Rupnow (Sep 6, 2022)

This engine is being worked on---slowly. After spending my entire summer building it, I'm taking my time in troubleshooting it.---Brian


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## Brian Rupnow (Sep 7, 2022)

Today, after a well deserved break away from engine building, I am in diagnostic mode. The engine runs (You seen the video), but it doesn't run smoothly nor consistently. The surest diagnostic trick is to pressurize the cylinder with compressed air, and see where air is leaking out. If you are testing the cylinder off the engine, you have to put it in a vice like I show, or the piston and rod will take off like a cannon ball as soon as you pressurize the cylinder. If you test the cylinder on the engine, the piston has to be at top dead center on the power stroke so that both valves will be closed, and you must devise something mechanical to prevent the crankshaft from turning. So, with 50 psi on the regulator---If you have air coming out the intake side of the cylinder head, your intake valve is leaking. If you have air coming out the exhaust, then your exhaust valve is leaking. If you have air coming out the other end of the cylinder, then your rings are leaking. Follow the pictures and it shows what I am talking about. There were no leaks in this set up I have shown. after this post I will check the other cylinder which is still attached to the engine.


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## Brian Rupnow (Sep 7, 2022)

In these pictures you can see the test rig as assembled on the work table in my office and actual test procedure being done with the cylinder and rod in my bench vice to keep the rod and piston from taking off like a rifle bullet.


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## Brian Rupnow (Sep 7, 2022)

So, what were the results? The cylinder tested in the vice is not leaking any air anywhere at 50 psi. The cylinder still on the engine is leaking a little bit around the rings at 50 psi. I may have pinched that Viton ring when assembling the piston and rings into the cylinder. I will pull that piston out and check the condition of the ring. Both sparkplugs are firing in the correct sequence as the engine is rotated by my variable speed drill. I may have a carburation problem, but will check that out as I continue my diagnostic testing.


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## Brian Rupnow (Sep 7, 2022)

An inside view of the cylinder head. There is a possibility that the end of the sparkplug is too shrouded by the cylinder head itself. As it is right now, the threads in the cylinder head fully engage the threads on the sparkplug. I don't want to deepen the sparkplug counterbore any more, because although it would allow the tip of the sparkplug to extend farther into the combustion chamber, there is too much chance of the smaller thread engagement stripping out the brass cylinder head threads. However, I can come in with a 5/16 endmill from the near side of the cylinder head and plunge about 0.100" concentric to the sparkplug hole. This wouldn't change the thread engagement at all, but would open it up around the tip of the sparkplug more, to give a better chance of the air/fuel mixture igniting.


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## Brian Rupnow (Sep 7, 2022)

This picture shows the same cylinder head. I have ran a 5/16" endmill down 0.100" from first contact. This doesn't do away with any thread engagement with the sparkplug, but does open it up so that the air/fuel mixture has a better chance of igniting.


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## Steamchick (Sep 8, 2022)

Hi Brian, I note that this counterbore will also slightly reduce the compression achieved. But I think it is a good idea anyway. What compression change has occurred?
K2


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## Brian Rupnow (Sep 8, 2022)

Steamchick--I didn't calculate it. The pocket is very small.---Brian


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## Brian Rupnow (Sep 12, 2022)

Things have been crazy/busy around here this past week. My wife organized a "Walk for Parkinsons" charity walk on Saturday. Weather was great, over 100 folks showed up and she raised over $32,000 for Parkinsons research. I've been working on a robotic work station for one of the big 3 automakers and this morning they changed everything that I've done in the past two weeks, but I still get paid for what I've done. Today I made a new piston for the cylinder which was leaking pressure into the crankcase, because  I couldn't stop it leaking past the rings. I think the previous piston had it's bottom ring too close to the wrist pin hole. Tomorrow I will pressure test that cylinder again, and hopefully the leak is fixed. I also learned the nasty truth about socket head capscrews today.---I love the look of them, but after you've tightened and loosened them about 5 times, the socket rounds off and then they can't be tightened any more, and even worse, the tight ones can't be loosened. Of course, I'm always an optimist, thinking they will only have to be tightened once.---HAH!!!


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## Vietti (Sep 12, 2022)

AIRC you used an O ring with 3 ci rings.  Maybe try the piston with only the o rings or with only the CI rings??


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## Brian Rupnow (Sep 12, 2022)

The new piston has only one Viton ring on it, closer to the top of the piston, farther from the wrist pin hole.


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## rick9345 (Sep 12, 2022)

Brian Rupnow said:


> Things have been crazy/busy around here this past week. My wife organized a "Walk for Parkinsons" charity walk on Saturday. Weather was great, over 100 folks showed up and she raised over $32,000 for Parkinsons research. I've been working on a robotic work station for one of the big 3 automakers and this morning they changed everything that I've done in the past two weeks, but I still get paid for what I've done. Today I made a new piston for the cylinder which was leaking pressure into the crankcase, because  I couldn't stop it leaking past the rings. I think the previous piston had it's bottom ring too close to the wrist pin hole. Tomorrow I will pressure test that cylinder again, and hopefully the leak is fixed. I also learned the nasty truth about socket head capscrews today.---I love the look of them, but after you've tightened and loosened them about 5 times, the socket rounds off and then they can't be tightened any more, and even worse, the tight ones can't be loosened. Of course, I'm always an optimist, thinking they will only have to be tightened once.---HAH!!!


over torqued always rounds the small ones .and or inexpensive Allen keys


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## Steamchick (Sep 13, 2022)

You really need a screwdriver-type torque wrench for the very small torques of small screws - and believe the torque figures from the manufacturer of the screws! I have a lb-in. torque wrench - max 120 lb.-in, and that is too big for sub-1/8" screws!
Then finding adapters to get a small hex end can be problematic!
I have some electricians nut spinners which are OK for those particular screws (8BA, 4BA), but hard to find for many small screws like 2.5mm hex. socket...
K2


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## Brian Rupnow (Sep 15, 2022)

After stripping the engine down to it's basic parts, I haven't found anything that would prevent it from running. I replaced the piston on the side that was leaking past the rings a little bit, and I've opened up the cylinder heads a little bit around the sparkplug ends. The Traxxas carb which I had originally ran was a bit questionable, so I have replaced it with a home made carb based on Malcolm Strides plans.  The engine is now reassembled, and I'm going over the second ignition coil as I write this.  The spark seems to be a lot weaker than I would like, but I have some more testing to do before I replace it. I hope I can sort that out, as a 12 volt coil costs $70 here. I may have to try and return the coil to the automotive parts house where I bought it and hope for a free replacement.


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## Steamchick (Sep 15, 2022)

Hi Brian, 3 checks immediately for what seems like a weak spark...
1: Battery voltage and current when "running"... and 
2: dwell angle - I.E. the part of the revolution of the cam when contact breakers are closed. On a Vee-twin, one is more than 360 degrees, the other less than 360 degrees. If the battery cannot handle the current draw of the coil, the current will drop significantly (Very visible on an analogue meter - but not a digital one?). So, in that case you may get a better spark with the longed dwell angle, and a poorer spark on the one with less dwell angle.
But most ignition systems are more than capable of providing good sparks up to 6000rpm or so firing 2 sparks per revolution! But "model" coils are possibly smaller/less robust than "car-type" coils?
3: The 3rd. check is the resistance of the circuit from coil through the contact breakers to earth (battery terminal). If this is higher than "not a lot" (continuity) then the spark will be weak. Clean contacts with alcohol. (Not abrasive, as the platinum is so thin nowadays, you'll rub it off with 2 wipes of emery!).
K2
P.S. Excuse me if you already have done these ...


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## Gordon (Sep 15, 2022)

Brian Rupnow said:


> After stripping the engine down to it's basic parts, I haven't found anything that would prevent it from running. I replaced the piston on the side that was leaking past the rings a little bit, and I've opened up the cylinder heads a little bit around the sparkplug ends. The Traxxas carb which I had originally ran was a bit questionable, so I have replaced it with a home made carb based on Malcolm Strides plans.  The engine is now reassembled, and I'm going over the second ignition coil as I write this.  The spark seems to be a lot weaker than I would like, but I have some more testing to do before I replace it. I hope I can sort that out, as a 12 volt coil costs $70 here. I may have to try and return the coil to the automotive parts house where I bought it and hope for a free replacement.


Just try switching the two ignition boxes or perhaps just the coil. I have had good luck with COP (coil over plug) coils. You can buy eight of them for less than $70.


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## CFLBob (Sep 15, 2022)

Gordon said:


> Just try switching the two ignition boxes or perhaps just the coil.


This.   If the poorly firing and properly firing cylinders reverse when the coils are swapped,  you've found the issue.


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## Brian Rupnow (Sep 21, 2022)

After spending a ridiculous amount of time fussing with this engine, I think I have narrowed the reason it won't run to be that wild and crazy intake manifold/fan mount system. The engine has compression, valves are timed correctly, and ignition is timed correctly. The one thing that I am seeing and I haven't seen this before, is that while the engine is being cranked with my variable speed drill it is absolutely not pulling any fuel from the gastank up to the carburetor. I tried this with a purchased Traxxas carburetor and with a home made carburetor.  This is a totally new one on me---haven't seen this before. At any rate, I have built a new fan support, which is totally independent of the intake system, and I have built two stubby carburetor mounts that work with Traxxas carbs---I have two new ones on order.


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## minh-thanh (Sep 21, 2022)

Hi Brian !
There's one thing I've been thinking about for a long time that I don't know if I should say......
  You should clean - really clean all engine parts before assembling and after assembling the engine
  Only one or a few small Swarfs will destroy cylinders, pistons, O rings...and affect intake valves, exhaust valves...
  And more , when the engine is clean, you will easily adjust everything and easily find the reasons that the engine does not run or does not run well, ....


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## Nerd1000 (Sep 22, 2022)

To check whether it's a fuelling issue, why not try running the engine on a squirt of starter fluid? If it fires and runs smoothly that rules out ignition issues.


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## Steamchick (Sep 22, 2022)

Can you make a simple gravity feed to the carbs?
I understand the difficulty of the large volume of intake manifold compared to the displacement of the engine. The manifold depression is not great enough to suck the fuel at cranking and slow running speeds... Maybe a faster cranking motor could help starting, but if you have fuel starvation nothing will resolve that except more fuel.
The twin carb solution was the answer for motorcycle V-twins back before I was born....

Good luck!
K2


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## Brian Rupnow (Sep 22, 2022)

You can not gravity feed these carburetors. They do not have a float and float needle to shut off gravity fed fuel. If the tank is higher than the carburetor it floods like crazy and pees all the fuel into the carburetor and then into the cylinder or out onto the floor. This type of carburetor uses venturi produced vacuum to suck the fuel up from the tank which is always located below the carburetor.---As far as keeping everything clean is concerned---I keep everything clean enough. May still be dirty on the outside, but it's clean where it matters.


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## Steamchick (Sep 22, 2022)

Thanks Brian, It was just a suggestion.... being a few thousand miles away means I can't just pop over and stick my nose in.... but I figured you were trying to lift fuel an inch or 2, when carbs usually only lift a half inch or less? And with reduced depression at start-up, maybe only a tiny fraction of an inch? The fuel tank is nearly the same level as the carburettor, so perhaps it just needs filling a little, to just short of flooding?
Ideas are free... but only the right one is more than worthless.
Cheers, you'll crack it soon.
K2


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## minh-thanh (Sep 22, 2022)

Brian Rupnow said:


> May still be dirty on the outside, but it's clean where it matters.


Yes, I'm sorry.
   Because I always make the engine as clean as possible
Each person, each way.


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## johwen (Sep 23, 2022)

Unless your carb has a throttle Brian a smaller choke bore will give better carburation at a slower speed and the engine will run smoother. Give it a try.
Cheers.
John


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## Brian Rupnow (Sep 23, 2022)

Jonwen---These carburetors do have a throttle.---Brian


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## werowance (Sep 23, 2022)

so Brian,  whats your ideas on why it wouldnt suck fuel with your original intake?  im not asking because i have a suggestion or anything,  just wondering is all.  are you thinking that one cylinder is letting the suction pass thru to the other cylinder during its intake stroke thus not putting enough suction on the carb?   or something like leakage around the solder joints or mounting joints? or what are you thinking?


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## Brian Rupnow (Sep 23, 2022)

I'm fairly convinced that it had to do with the intake not sealing tightly enough to the cylinder head at the flanges----or---When the one cylinder was on the intake stroke, the other cylinder may have had the piston in a position to let air pass thru it to the cylinder which was on the intake stroke, so that there wasn't enough air passing thru the carb to create the venturi effect, which creates the suction to pull gas up from the tank. Both ignition systems are working okay, giving the right amount of spark at the correct time. The valve opening sequence is correct, as set by using a degree wheel. Both cylinders are well sealed by rings and valves, --when I put 40-50 pounds of air into the cylinder with my adapter that screws into the sparkplug hole, they are not leaking anywhere. The rocker arms are set for 0.010" clearance from the pushrods when the piston is up on compression. I did notice that the flange on the cylinder head which is supposed to be in line with a flat space machined into the cylinder in the same spot wasn't perfectly flat--The flat spot on the cylinder stuck out about 0.010" from the flat spot on the cylinder head. I have since filed the cylinder flat spot to be perfectly flat and in line with the flat spot on the cylinder head where the flanges match up with the intake manifold.  I was using cardboard gaskets there, but they may not have totally filled the gap created by the flat spots not being perfectly aligned.


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## Steamchick (Sep 24, 2022)

Hi Brian. I am looking forward to your results when your twin carb set-up is fitted. I think that the separation of the 2 intakes - with shorter intake tracts and smaller volumes - will make a big difference.  
I read the comments about one cylinder try to suck while the other has the Inlet valve open... surely your valve timing diagram can confirm this? But I would have expected these timings to be well spaced...? Looking at my Moto Guzzi valve timing curves, based on crank angle, inlet 1 opening 18 deg BTDC  - call this TDC zero degrees. So we have zero degrees, inlet 1 open, until 230 degrees. Then inlet 2 opens at 432 degrees, and closes at 680 degrees. Then inlet 1 opens at 702 degrees. = 18 degrees BTDC  at 720 degrees, or zero degrees. But my engine is a 90 degree V-twin. The gaps where both valves are closed are 202 degrees and 22 degrees. I think your V is closer than 90 degrees, so those closed angles will be closer in value....??
Hope you get it figured out soon....
K2


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## Brian Rupnow (Sep 24, 2022)

I'm still waiting for my new carburetors to come in.


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## Brian Rupnow (Sep 24, 2022)

This morning held a startling revelation!!! I got up early and sneaked down to the bat cave, and as I was pondering why my engine wouldn't start when everything was adjusted correctly, I was fondling the carburetor. When I had been trying to start the engine a few days ago, it had good spark, the valve and ignition timing were set just right, but when I tried to start the engine it simply would not suck up fuel from the gas tank. I've never seen that occur before, and it left me scratching my head and made me decide to move on to two carburetors with individual short inlet pipes and a separate stand for the fan.---And as I fondled the carb, the thought suddenly appeared in my head "I wonder if the carburetor is letting the fuel thru it?"--So, of course, I picked up the carburetor and tried to blow air thru the inlet where the flexible gas line attaches to it. (Another sort of "Blow yer guts out" kind of thing). And it was plugged tighter than a fishes arse. That tiny little tube 0.055" outside diameter x 0.025" inner diameter was plugged absolutely solid. I tried high pressure air to clean it out--no luck. I tried to push a very small diameter wire thru it---no luck. NOW I know why the carb wasn't sucking up any fuel from the tank. Remember, this engine did run briefly, but that was with a different store bought carburetor on it.  Big mystery is solved!! As soon as my new Traxxas carburetors arrive, I will try and start this engine again, with dual carburetors on it.


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## Brian Rupnow (Sep 24, 2022)

I remembered that I had a couple of sets of cleaner wires for cleaning oxy acetylene tips with. I finally persuaded a 0.018" wire to pass thru the blocked tube. If I didn't clean it right now, I'd probably pick up the same carb in six months and be puzzled all over again when it didn't work.


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## petertha (Sep 25, 2022)

Mesh fuel filters & tank 'clunk' filters come in a variety of flavors in the RC world. Highly recommended to avoid those problems. 
BTW pushing wire through to clean the passages can sometimes cause more damage depending on the spray bar & needle valve area because you risk driving the debris into passages which are even smaller yet.


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## Ghosty (Sep 25, 2022)

Petertha,
The one in the middle is for methanol only, they melt when used with petrol. The blockage could also be because of the oil used, some oils attack brass.
Cheers
Andrew


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## petertha (Sep 25, 2022)

That's a very good point, thanks @Ghosty. The examples I showed are intended for methanol fuel. But they do make ones for gasoline as well, so confirm before you buy.


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## Brian Rupnow (Sep 25, 2022)

Thanks guys.---Brian


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## Brian Rupnow (Sep 26, 2022)

Last week I ordered two new Traxxas 4033 carburetors from Ebay. Had a terrible time logging in to Ebay, so I bought and paid for them as a "Guest". When the sale was completed I thought it kinda weird that I didn't get a confirmation nor a tracking number. Next day I asked goodwife to check and see if the Visa had been charged.---It had. Carburetors were supposed to arrive today, but nothing showed up here. I called Ebay, and they had no record of a sale being made in my name. After pounding my head for a while, goodwife said "Did you talk to Ebay American or to Ebay Canadian"?  Uh, no--I didn't know there was an Ebay Canadian. So, I chased down a phone number in Canada and called it. Got a very nice young lady who found a record of the sale (Hurray!!) and she said they would arrive here on the 30th of Sept. Then she said that since I bought them as a guest instead of logging in to Ebay, I wouldn't receive a confirmation nor a tracking number. I asked her what part of Canada she was in, and was told "Florida". Wait!! What?? I called Ebay Canada, how come I got someone in Florida? She told me "That's how the system works." I'm not getting older, I'm going insane!!! Florida in Canada. Aw Jeez, I shouldn't have got out of bed this morning!!!


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## ShopShoe (Sep 27, 2022)

Brian,

You're lucky she was in Florida, not overseas. I also have come to understand that some telephone support is provided by inmates in prisons sometimes.

I'm enjoying your saga of this project.

Thank You for the updates.

--ShopShoe


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## Brian Rupnow (Sep 30, 2022)

Yayyyyy--My new carburetors showed up in my mail today!!! They look awesome on the engine. I have never built anything before with dual carburetors. Tomorrow I will make up some linkage and gas lines, and say a prayer to the small engine gods and maybe I'll have a runner.


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## SteamChEng (Sep 30, 2022)

Brian Rupnow said:


> Yayyyyy--My new carburetors showed up in my mail today!!! They look awesome on the engine. I have never built anything before with dual carburetors. Tomorrow I will make up some linkage and gas lines, and say a prayer to the small engine gods and maybe I'll have a runner.



Excellent!  Best of luck on the final few bits, Brian!  We're all looking forward to seeing (and hearing!) it run!


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## Brian Rupnow (Oct 1, 2022)

YES!!!--Engine is up and running on it's own. Both cylinders are firing, and both carbs are pulling up fuel from a Tee just at the discharge side of the fuel tank. Should have a video up sometime soon.


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## Brian Rupnow (Oct 1, 2022)

And yes kiddies, we have a runner. Obviously I have some tuning to do, but this is very heartening. I have a strange arrangement of linkages on the carbs, temporarily, but thats because that is the setting where it runs best right now. I will post a better video when I get the final tuning sorted.---Brian


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## stevehuckss396 (Oct 1, 2022)

Congratulations Brian, we'll done sir.


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## Brian Rupnow (Oct 1, 2022)

Thanks Steve--Not long after taking that video I wanted to change the sparkplug on the right bank, as it seemed to be misfiring. I took the old plug out, put new plug in, tightened it just a bit---and the top twisted off the sparkplug leaving the threaded section still screwed into the brass head. Oh Poop!!! Checked my easy outs, and didn't have the right size. On Monday I'll buy the right size Easy out, but to be truthful I've never had much luck with easy-outs. I may have to take the head off and try to get the threaded section of plug out. There is a ton of work in making one of those heads.


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## GreenTwin (Oct 1, 2022)

Nice work.
Runs like a champ !

.


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## stevehuckss396 (Oct 1, 2022)

Take a drill bit just a hair bigger than the hole and try to drill it out from the inside. I would be shocked if it didn't break loose and zip right out.


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## Jojo (Oct 1, 2022)

Congratulations Brian!
I admire your ability to design and create so many engines.
I finish my engines at the rate of one every 3 years or so!


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## Badhippie (Oct 2, 2022)

Brian
Excellent work you stuck with it and figured it out. Very nice engine


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## Brian Rupnow (Oct 2, 2022)

The lord loves me!!! I modified a nasty old Easy-out that was bent  all out of shape, and the broken off spark-plug end come out easy peasy. I have never liked Easy-outs, and have never had much luck using them, but today it worked like a charm. I didn't even have to take the cylinder head off the engine. I started to silver solder some brass/bronze parts together to make a decent looking spring return bracket for my throttle linkage, and couldn't get enough heat out of my oxy acetylene rig to make the solder flow. My oxy acetylene rig is only about 50 years old, and has served me well, but the regulators are frozen at a low pressure setting, and turning them higher doesn't change the strength nor size of my torch flame. New oxy acetylene rigs seem to cost between $500 to $600 dollars here in Ontario, but you can buy replacement regulator sets for about $75 each, and I need two.---Will talk to my welding suppliers tomorrow about it.


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## Gordon (Oct 2, 2022)

Brian Rupnow said:


> The lord loves me!!! I modified a nasty old Easy-out that was bent  all out of shape, and the broken off spark-plug end come out easy peasy. I have never liked Easy-outs, and have never had much luck using them, but today it worked like a charm. I didn't even have to take the cylinder head off the engine. I started to silver solder some brass/bronze parts together to make a decent looking spring return bracket for my throttle linkage, and couldn't get enough heat out of my oxy acetylene rig to make the solder flow. My oxy acetylene rig is only about 50 years old, and has served me well, but the regulators are frozen at a low pressure setting, and turning them higher doesn't change the strength nor size of my torch flame. New oxy acetylene rigs seem to cost between $500 to $600 dollars here in Ontario, but you can buy replacement regulator sets for about $75 each, and I need two.---Will talk to my welding suppliers tomorrow about it.


You can buy rebuild kits for the regulators for about $25/$30 US. The diaphragm gets brittle and will not work. Ask your supplier.



			https://www.amazon.com/Victor-SR250D-Regulator-Rebuild-Diaphragm/dp/B06W5JZL4Z/ref=sr_1_2?gclid=CjwKCAjw7eSZBhB8EiwA60kCWwUN8Ns8qsSFaj8ALzIbPcu875cJOF6ZLzxbkEyyRfUDdebDS15OVxoCTwgQAvD_BwE&hvadid=192825101466&hvdev=c&hvlocphy=9051962&hvnetw=g&hvqmt=e&hvrand=17818618193630061880&hvtargid=kwd-301599975723&hydadcr=11987_9729879&keywords=victor+regulator+repair+kit&qid=1664754630&qu=eyJxc2MiOiIzLjY2IiwicXNhIjoiMy4yMiIsInFzcCI6IjIuNTAifQ%3D%3D&sr=8-2


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## Steamchick (Oct 3, 2022)

Hi Brian, I admire your fortitude as well as your engine expertise. I have a couple of engines that have beaten me by becoming "show" models, not runners! - May be one day I'll fix the issues - if I ever find what is wrong.
But you stuck in there and made it happen.
Great stuff, and a great engine! 
Now make a Hardly Able-to style frame, forks, gearbox, etc. and have a model motorcycle a very small person can ride... ?
It is a beautiful job!
K2


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## Brian Rupnow (Oct 3, 2022)

Well, that wasn't too horribly painful. New tank of argon for the tig welder, $60, New tank of acetylene--$50, New hoses and fittings for oxy-acetylene rig $45, new acetylene regulator--$125, Hazardous material charge $10 and $35 tax. Grand total of $306.59. I'm back in business again, and I did get the silver solder to flow on that joint I was working on yesterday. Some of that material was 3/16" thick, so it took a lot of heat to get things to flow.


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## Brian Rupnow (Oct 3, 2022)

And---TA-DA---We have a throttle return spring and bracket added.


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## werowance (Oct 4, 2022)

i like it.  the knurled tip that you are pulling to "give it more gas" is that an adjuster screw to for lack of better words adjust the idle speed?  or is it just knurled to give you something to grab hold of to pull it?


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## Brian Rupnow (Oct 4, 2022)

It is just knurled to look pretty and give me something to pull on. There are adjustments for fast or slow idle on the carburetors.


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## Brian Rupnow (Oct 4, 2022)

Message here for Steve Hucks--Look at my spark-plug boots. Both sparkplugs are 1/4" thread. The boot on the left works fine. The boot on the right is shorting out right thru the boot material to the nearest cooling fin. It's like a miniature lightning storm when the engine is running. Do you sell spark-plug leads and boots like the one on the left?---Brian


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## Brian Rupnow (Oct 4, 2022)

And now, it's time to go all scientific. The engine runs, but it doesn't run the way I like it to. The left hand cylinder runs like a champ, the right hand cylinder runs some of the time. Some of the time, it doesn't run. and when it doesn't run, it puts so much drag on the left hand cylinder that it stalls out under the load of carrying the non firing cylinder. Generally I use a degree wheel to set the valve timing, and lay the sparkplug out on the cylinder head so I can manually crank the engine over and watch to see when the spark occurs relative to the piston position. Somehow, that doesn't seem to be working for the right hand cylinder.---So, tomorrow I will once again get my degree wheel out and set the valve timing on the right hand cylinder. (The engine has a camshaft for each cylinder bank). Then I will pull the cylinder head off and put a dial indicator on the piston so I can set the spark timing up to occur exactly when the piston is at top dead center. The right cylinder has good compression, and the engine has "loosened up" considerably from running. I have tried a couple of different sparkplugs in that cylinder, and it makes no difference. Other folks have had better results with this style of engine, so I don't think that the problem has anything to do with the engine design.


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## Vietti (Oct 4, 2022)

Switch carbs??


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## johwen (Oct 5, 2022)

Why not just run the right cylinder on it's own. Leave the plug out on the left cylinder or just hold the exhaust valve open on the left. This would make it easier to ID the cause of the problem. Is the cam timing identical with the left side?


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## metalmangler (Oct 5, 2022)

A bit of a long-shot, but would it be worth trying swapping the camshafts ?


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## Brian Rupnow (Oct 5, 2022)

All good suggestions guys. I will let you know what happens.---Brian


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## stevehuckss396 (Oct 5, 2022)

Sorry Brian that one looks like an s/s boot from cncengines.com. the only thing I can offer is a longer plug. I have standard length, 1/8, 1/4, and 3/8 extended length.

Also I don't know if the auto parts stores in your part of the world has them but you can make a thicker boot using vacuum fittings.


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## wgpeters (Oct 6, 2022)

Is there any chance that one of your cams is 180 degrees off?  When the first cylinder fires. the next cylinder should be starting exhaust, not compression.


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## rsholl (Oct 6, 2022)

Brian, couldn't find what spark plugs you are using. Let me know and I can send you another cap like you are using on the left cylinder.


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## Brian Rupnow (Oct 6, 2022)

Roy--I don't know who made these plugs. I may have bought them from you. They have a 1/4"-32 thread and an electrode like an automobile sparkplug. The overall length including electrode is 0.987", and measured from the porcelain end the porcelain (including the brass button on top) is 0.463" long. The porcelain is 0.178" diameter. (It may not be porcelain, but it is white). I would like to buy a dozen of the boots, with a dozen 14" long wire leads attached. The leads measure 0.100" diameter. I have a different email since I last dealt with you, contact me with a price in American dollars at [email protected]  ---Brian


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