I don't get it. Did you crank get cut down? If so you need 2 thou oversized bearings.

I can't think of why you would need 2 thou undersized...

Guy doing my work said I need 002 undersize main bearings and the crank is stock the motor has different pistons tho

You will never need undersized bearings...

Put some logical thought into it:

1. You cannot feasibly add material to the crankshaft, warranting smaller, undersized bearings.
2. When enough material is removed from the crank, i.e. when it is cut, oversized bearings compensate for the material taken from the crank.

The only time I could think of is if the machine shop resurfaced the bed plate to block surfaces... But when they do that they are supposed to align hone the block...

dsmcrzy said:

The only time I could think of is if the machine shop resurfaced the bed plate to block surfaces... But when they do that they are supposed to align hone the block...

Click to expand...

Have to align hone, or the bores are not round anymore.

You sure he did not mean 20 thousandths (0.020" or 0.05 mm)? Two thousandths is not a normal cut at all.

Yea should have changed 'supposed to' to 'have to'. My bad.

Different pistons has no affect on the main bearings size either. It's possible the machinist is talking about rod journals, but again it would be over sized, not under and 20 thousand, not 2.

clevite rod bearings cb-1643p, come in std, 25mm, 50mm

cb1643p25mm
cb1643p50mm

part numbers for all 3 :3