Engines > Restoration of Model Engines

Rebuilding my Upshur vertical single

(1/3) > >>

Art K:
Hi everyone,
Some of you who were at the Zanesville engine show know that I had my Upshur single apart for repairs. Over the last year or so I had been noticing that it was running worse & worse. Before the show I took the head off to see what was wrong and found about a 16th of an inch of carbon built up on everything in the combustion chamber. Then yesterday I took apart the crankcase, this is what I discovered.

The Piston looks much worse in the photo than it really is. But as you can probably see the rod journal is very rough, and the rod bearing is oblong about .040". There are scuff marks on both sides of the connecting rod from it hitting the cylinder. Also it shifted up enough to hit the center of the cam.

This Is what it looked like in its prime. I think at the least a new rod and crank are needed. I had redesigned the head already, had hoped to have that in time for the show but the computer for my mill died so that has been postponed till my computer guy has healed up from surgery after his vacation. No I didn't ask.
Art

cheepo45:
My Upshur horizontal has been rebuilt several times.
I just polish the crank as much as I can, and trim the rod cap faces and ream or rebore the rod to the proper clearance.
You may have to add some clearance to the sides of the rod so it doesn't hit the cylinder.
That gets me another 5 years or so.
 Scott ;)

Art K:
Scott,
I've been running it for ten years and this is the first time I've had to open her up. The rod is past any reworking and the rod main is .002 under w/o any cleaning up at all. I am considering replacing the bearings as well, although they may be ok. The photo doesn't show how visibly oblong it is.
Art

cheepo45:
I think you are correct in making new parts with the crank at -.002.
It's kind of cool to actually wear out one of your creations.
I run my IC engines all day at the shows. My Upshur is on its 6th set of rings and its third cylinder!
I hope your rebuild goes well.
 Scott

Art K:
Here's a better photo of the rod. By the way I have no idea what grade of aluminum this is. It was what ever I had laying around. Is there a specific grade of aluminum I should use? I am considering using a bearing of some sort on this, though I'm not sure it's worth the effort.

After all in the ten years it's been running I discovered it would run 7400 RPM.
Art

Navigation

[0] Message Index

[#] Next page