Engine rebuilds

[Larry Helms]

hello all.. I have two fairbanks engines that need rebuilds. One is a 6hp that was stuck, I have managed to get the piston and rod out of the bore, and the other one is a 2 1/2 or 3 hp that has no compression. The main bearings on both engines seem ok. What tolerances on the rod should I have? thanks

[Kevin O. Pulver]

I don't know what the manuals recommend. (reprints are available) but I would suggest about 3 thousands rod clearance. That would be about the thickness of one piece of typing paper. I would just keep adding and removing shims until you have a light drag on the bearing. If it's too tight it will heat up while running. Keep an eye on it. Of course too loose, it'll knock . Keep it greased, and it will wear in if only a bit too tight. It won't give you much trouble at all especially since you won't likely have a load on the engine. Maybe you could search the archives here for more information. Kevin

[Jim Tremble]

Originally Posted by Larry Helms

The main bearings on both engines seem ok. What tolerances on the rod should I have? thanks

Larry

From what I have been tought over the years, OIL clearance is .001"-.003". Grease clearance is .003"-.005".

You can check the clearance with Plasti-gauge. You can get it at your local parts store.

As Kevin mentioned, if the bearings feel hot, they are to tight. If just a bit warmer that the cast iron around them, they are OK.

Hope this helps you,

Jim

[Larry Helms]

Thanks Guys, what about the piston end ?