Why is it that when you get your crank ground lets say 10 under, the rods have to be sized. don't 10 over bearings account for this?

 

I think the rods are resized because they are out of round. Y'know, the usual grinding of the cap, and re-boring it. The rods end up being the same diameter as when they started, just more round.

Are all the journals usually ground .010" under? I thought it was just the main journals, anyways. Anybody know?

 

the journals can be gruond many sizes. even .001 to just clean them up. but id say most common is 10 under. other sizes it can be are 20 under and 30 under

 

you don't have to resize the rods when you machine the crank. i would resize the rods if i changed bolts.

 

You can grind both the rod and main journals on a crank. That is where the 2 numbers come from. If you have a .010 - .010 crank, that tell the mains and rod journals are turned down.