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.