The Ford Barn

Bored&Stroked · 11-29-2018, 06:36 PM

I run the old standard performance clearances of .001 per inch of journal size. This gets you in the ballpark. Depending on the application, I may run more in the rear main - like closer to .003. If you're racing and the clutch is getting really hot, then the heat transfers to the rear of the crankshaft - taking up some of the clearance.

If the crank is already ground, then sometimes I need to buy multiple sets of main bearings to get the exact clearances I'm looking for -- sometimes they vary by .001 or so . . . just the way it is. We don't have the luxury of .009 or .011 bearings (for a .010 crank) - to 'tune' the clearances. The best way to do it is to buy your bearings FIRST - then use a very accurate dial bore gauge to measure them in the block, then give the numbers to the crank grinder. This method is by far the BEST - and should give you the exact clearances you desire (if the machine and operator are top notch).

With all this babble, I will say that I'd rather have it a bit "loose", than too tight . . . loose is fast, tight is death! LOL

11-29-2018, 06:36 PM	#11
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,723	Re: Bearing clearance I run the old standard performance clearances of .001 per inch of journal size. This gets you in the ballpark. Depending on the application, I may run more in the rear main - like closer to .003. If you're racing and the clutch is getting really hot, then the heat transfers to the rear of the crankshaft - taking up some of the clearance. If the crank is already ground, then sometimes I need to buy multiple sets of main bearings to get the exact clearances I'm looking for -- sometimes they vary by .001 or so . . . just the way it is. We don't have the luxury of .009 or .011 bearings (for a .010 crank) - to 'tune' the clearances. The best way to do it is to buy your bearings FIRST - then use a very accurate dial bore gauge to measure them in the block, then give the numbers to the crank grinder. This method is by far the BEST - and should give you the exact clearances you desire (if the machine and operator are top notch). With all this babble, I will say that I'd rather have it a bit "loose", than too tight . . . loose is fast, tight is death! LOL