Hello All,
I have a 502 carburator with -3 flat top pistons with the heads I will be running it brings the CR to 8.5 if using the same heads and changing the piston to make a CR of 9.5 would I gain a huge amount of power or should I just keep the pistions I have now.

by going one full point in compression you will stand to gain a decent amount of power
exactly how much is not going to be a definate answer but you will definately gain some power,

what heads are you running on the setup ?
if aluminum you can go up to around 10 to 1 even a little higher depending on what gas you want to use

Do you have enough piston to valve clearance to mill the heads to increase the CR?

I'm going to run a set of merlin heads 119cc . I would rather change the pistons than mill the heads. If anyone has a sey of pistons with a 4.47 bore shoot me an email. Thanks Jeff