I am puzzled with what way to go. I have ordered a new main bearing set for my 1956 235 truck engine and they say I need to buy shims for under the main bearing caps but when I read the supplement manual it says they discontinued the shims in 1956. Do I need them or not is my question.
Use a Plastigage to see what the clearances are when the caps are torqued up. You may have to buy some shim stock and make up some shims.
Know people aren't going to believe this. But back in the day early 60s a buddy who actually became my best man was putting together a 312 for his 57 Ford. It was the weekend and he had to get it back together. He was 16 and already married it was his only car. Anyhow he was working in a little garage off from his bosses place of business a printshop. He realized his main bearings were too big for his crank he told his boss what had happened and said what am I going to do? His boss said look around the solution is all around you. He looked but nothing was obvious. His boss then told him paper incredulous he thought boss was joking. He told him good paper was strong and would work. Anyhow they found a good grade of paper that was right thickness cut shims for each bearing and assembled the motor. He put it in the car on Saturday night Sunday we broke it in on way to Onondaga Dragway. That car ran fine and he hammered it until he traded for a new 64 Galaxie.
Chevy stopped using main shims in 54 or so. If your engine did not have them you don't need them. As said Plastic -gage them to be sure.
The Jalopy Journal
