You can use .001" if the crank is undersize, or many builders will mix shells,, say using one standard and one .001" if you only need to make up .0005". There are also "x" bearings, or extra clearance if the crank is a little "fat". That's one of the reasons the standard crank has always been so desireable, the ability to get bearing clearance exactly where you want it.in what instance or circumstance could u use a .001 under bearing for ur rods & mains?
FastRat