327 overbore, .010>.020>.030?

[Alex V.]

It seems a lot of times the first overbore on a SBC is .030". The correct ("657" code YS) block I've procured for my Suburban is standard bore, and when I rebuild it I'd like to take as little as possible so as to allow another rebuild in the future. It'll be a bone stock rebuild so surely pistons are available in .010 or .020. Is it very uncommon for the wear to clean up at less than .030", or is it just cheaper to overshoot and have more of a gaurantee of cleanup with the greater overbore?

[YoungPup1977]

It all depends on cylinder taper and wear in each cylinder, not every block is the same....measure every cylinder than you will know what you need to do.
OK...measure twice, bore once....its like weighing each rod, you take the rod that weighs the least and make every rod the same weight....but you have to weigh each rod first....

[GASoline71]

The 350 in my 1972 is the original block and that engine had a lot of miles on it before I rebuilt it. My machinist took it .020 over and it cleaned up fine. I was pleasantly surprised as I was expecting it to go at least .030. Just make sure you tell your machinist what you are looking for. It might be fine at .020, but it might need to go bigger.

Gary