Whenever possible, I hand-fit Babbit rods before adjusting the oil clearance. Remove all the shims, coat the bearing area with Prussian Blue, and gently snug the rod cap nuts so there's a moderate amount of drag as you rotate the rod on the crankshaft. Disassemble, and look for bright (tight) spots. Carefully scrape the high spots with a tool made by hollow-grinding a 3-corner file to sharp edges. Reassemble and repeat until you get a smooth smear with no tight spots. Repeat for all six rods, then go back and start shimming for oil clearance. Put a small piece of .0015" shim stock between the rod cap and the crankshaft, and add shims until the rod will turn with only a slight amount of drag. Repeat for all the rods and make sure the shim pack stays in its proper place. If necessary, one more thin shim can be used on one side to split the difference between "too loose" and "too tight". Plastigage is OK for checking, but it leaves a lot to be desired for setting up clearances.
Of course, when I learned the above procedures, Plastigage was a new kid on the block, and my mentors didn't trust it much. They were wise men!
Jerry
