Hi guys, I have a question maybe someone can help me out with. I have a motor I just bought that looks like it has a fresh stock rebuild done to it but I want too boost the compression some by changing the pistons. It looks like the rebuilder already balanced the crank since it has different size holes in different places. Is there any shallow dish pistons that I can swap out with the stock 455 72 pistons and not have to rebalance? Also how much do the stock 72 455 low compression pistons and pin weigh? My rookie guess would be if the new pistons weight about the same I should be o.k. for a street car. I appreciate everyone's help on this site. Also I did order a tech manual from Mondello but just waiting for it.

 

You can change the pistons to boost compression but if the rotating assembly truly is balanced, it will need to be balanced again. The machinist may be able to match piston weights for each piston replaced but that is going to be a lot of work. Have you considered a thinner head gasket? Or milling the heads? Those will boost compression as well.

Do you know what the compression ratio is as the motor sits right now? What is your goal?