on a 350 small block chevy eng,could anyone tell me what the spec should be for main and rod bearing oil clearance,and would standard bearings have the correct oil clearance for both if no work has been done to the crankshaft.all answers will be helpful


thanks to all

CaptainRich

Standard clearance is, has been, and should always be: .030"
You should check this with Plasti-gage to make certain.

curtis73

Uh... how about adding another zero there Rich

Typical generic SBC tolerances should range between .001 and .002", but tolerances on the end bearings can vary. Often times the #1 main can be as little as .0008". .003 is a little loose for my taste, but it can be fine with thicker oil.

curtis73

In a word, no. A used crank will have egg-shaped journals. Simply putting new bearings on a used crank is like putting new linoleum on an old lumpy floor. Putting new bearings on an old crank can be fine, but while its out, why not spend a hundred bucks and have it remanufactured? A machine shop will recut the journals and repolish them.

The bad side is, often times putting new bearings on old journals will cause a spun bearing which damages the block and is big money to fix.... or sometimes can't be fixed.

curtis73

Sorry about the big disagree flag, Captain Rich. I'm new and I'm still learning how to rate things. Is there a way I can remove it?

CaptainRich

I stand corrected.
My clearance should have been stated as .003"
And clearances should always be checked in order to select the proper sized bearings.

CaptainRich

You can't remove it.
My post was inaccurate.
Being new has nothing to do with it.
Welcome aboard!