I once read on the forum that when cars left the factory there were no shims in the rods. I went out this evening and took a rod cap off an engine I got a week or 2 ago and no shims. I pulled the head off and it has Ford script standard pistons with little wear on the cyl walls. I didn't check with plastigage but I could find no looseness in any of the rods. I'm thinking maybe this engine wasn't run much. It's a replacement block, no serial #'s. My question is, how did people initially adjust bearings? By filing the caps? Then over time all the caps were filed and shims were supplied when new babbitt was poured? I'll check the clearances this weekend, but I've never disassembled an old motor where something wasn't worn out.