Even with the new design main bearings, it's a definite possibility that you might need to use shims to establish the correct oil clearance. Unless your machinist is willing to do a line bore job with four different bearing bore diameters, (most won't even attempt it) shimming for the right oil clearance is almost a "must do" situation. One main bearing on John's 261 needed a single shim to correct the clearance, and it was machined for the later model bearings.
BTW- - - -I've got the line bore tooling and I know how to handle that little chore, but I'm older than dirt!
Jerry
I hear you. Thankfully I'm blessed to have a good friend that's an amazing machinist. He owns a local performance engine machining/building business. He isn't exactly crusty yet, but he has some years on him. He has a lot of the obscure knowledge to work on old iron also. Like me, what he doesn't know he sees as a challenge to learn something new. In addition to all the modern equipment and dyno he also has a lot of tools that probably are now considered oddities and are mostly found in museums. I know he won't want to use shims and he'll do what it takes for me. Maybe he'll say to just use shims. Who knows. If he's alright with it I'm alright.
In the end, when I assemble it, I'll be comfortable with the choices.
