Upshur's opposed twin engine

[minh-thanh]

I'm having a hard time getting my head around this.---

Simply - because : where one cam operates the exhaust valve on both cylinders and the other cam operates the intake valve on both cylinders."
You just think of it as the engine on one side and when you align the lobe for that engine it will be exactly aligned with the other engine on the opposite side.

 

[mdanna]

Hi Brian!

Great job you are doing with your engine!
I have been trying to build valves and valve seats for a four stroke engine that I am building.
I was unsuccessful, as the valve doesn't seal properly.
Could you show how you make them?

 

[Brian Rupnow]

Today was kind of a write off type day. I went for my last physio appointment and was told that I had "progressed nicely" and didn't need any more physio appointments. I had it confirmed by another source that the angle between the two cams is indeed 105 degrees on this engine. I set the assembled engine up on my test bench, filled with oil and drove it with an electric motor for 20 minutes to get rid of any tight spots. I cut all of the pushrods to finished length and installed them, and set the valves to 0.005" clearance--not sure yet if I have to put relief slots in my cylinder heads for the push-rods or not. I read thru the instructions from Upshur once again about the distributor and decided that tomorrow I would buy some #2-56 threaded rod or at least some brass bolts with long threads that I can cut off and use for distributor terminals. I still have to put a keyway in my flywheel and in the crankshaft end that the flywheel sets on. I also have to set the engine up on my starter stand and drill and tap four holes to bolt the engine to it. That's probably enough work to keep me occupied tomorrow.----Brian

 

[Jasonb]

Gordon confirmed it was 102 Deg not 105

5 Thou is a lot of clearance for a small engine. You are unlikely to get the duration of valve opening with that much clearance.

 

[Brian Rupnow]

Today, it didn't take too much to wear me out. I drilled and tapped the engine sub base to hold a condenser for my ignition, drilled and tapped my starter mechanism top plate for the Upshur engine bolt pattern, milled a keyway in the crankshaft and cut a keyway in my flywheel. That doesn't sound like a lot, but I'm tired out now.

 

[cheepo45]

Great to see you back in the shop! I always look forward to your posts.
Scott

 

[Brian Rupnow]

Thanks Scott--No work today---All my aches and pains have caught up to me today, and I'm hobbling around like somebody's old granny. I still have to cut some clearance grooves in the cylinder heads to clear the pushrods, and time the cams. I called my nut and bolt guys yesterday and they don't carry any bolts nor threaded rod size 2-56 so I can either attempt to make my own---questionable.--They need to be made from brass, for the distributor so I will wait until Monday and try a different nut and bolt store (we actually have two such in Barrie).

 

[pileskis]

Thanks Scott--No work today---All my aches and pains have caught up to me today, and I'm hobbling around like somebody's old granny. I still have to cut some clearance grooves in the cylinder heads to clear the pushrods, and time the cams. I called my nut and bolt guys yesterday and they don't carry any bolts nor threaded rod size 2-56 so I can either attempt to make my own---questionable.--They need to be made from brass, for the distributor so I will wait until Monday and try a different nut and bolt store (we actually have two such in Barrie).

Try a hobby shop.
They usually have screws of that size.

Sid

 

[Brian Rupnow]

Sid--There is one hobby shop in Barrie. I will ask them on Monday.---Brian

 

[Brian Rupnow]

I couldn't let the entire day go by without doing something.----So----I milled grooves in the cylinder heads to clear the pushrods. You can't see what I have done, because the grooves are hidden by the pushrods. I can slide a piece of printer paper between the heads and the pushrods without it jamming up, and a miss is as good as a mile.

 

[petertha]

I was going to suggest an RC hobby store. For sure they would have steel 2-56 fasteners & threaded rod but I'm less confident about brass. They are not difficult to make in the lathe with a die & then you have control of other features if necessary. I made M3 pushrod adjusters from O1 for my radial. Brass would be easier yet.

 

[Jasonb]

They should not be hard to make, turn a bit of brass down to size and run a die down it in the lathe. Brass is easy to machine and unless your die is blunt will thread easily. If I can do it down to 0-80 and smaller on a similar lathe to yours it should be easy doing 2-56.

Did these in the week from 303 Stainless at M2 they are just a bit smaller than a #2

 

[toolsrul]

These two rather horrible little parts are "oil slingers" which bolt to the underside of the con rod caps and sling oil all over the inside of the crankcase when the engine is running. They are horrible because non of my machinery is really intended to make parts this small. So, by default, they are made with sheet metal "snips" and are irregular and ugly. The only good thing about them is that they are down inside the engine where nobody will ever see them.

Hi Brian,
Sure glad to see you at it again. I see these parts would make your list of parts you can make on your bench top cnc mill if that project is still being kicked around. The picture I sent 3 of the angled brass parts are connecting rods for a J. Ridder Euro 50 micro stirling engine I’m in the midst of building, the rectangular part is a bearing support & the other silver connecting rod was an experiment on how thin of material I can machine. It is .004” thick shim stock mild steel since I didn’t have .003”.
I see you have lots of people rooting for & are glad you’re back, you keep us interested.


George

 

[Brian Rupnow]

Jason--I may be having a total mind fart here, but I've been messing around with cam angles all afternoon and I simply can not see how 102 degrees lobe separation on the cams can work. If the inlet valve begins to open when the piston is 15 degrees before top dead center, and the exhaust valve begins to open when the piston is 40 degrees before bottom dead center, then I don't possibly see how 102 degrees can work. I'm not usually this thick, but I'm missing something.---Brian

 

[Gordon]

Look at the color diagram that I posted before. That shows the total cycle. What you have to look at is the 102 x 2 = 204 is the cycle, not the 102. The 102 is only because the cam turns at 1/2 the crank rotation. Forget 102 and think 204.