Does porting and polishing your heads affect the compression ratio?
jimbo

 

nope

 

ultimately i know that piston cc's (dish, flat, dome) decide the compression ratio but doesn't the volume of the the combustion chamber contribute towards the compression ratio. And with ap&p job they usually port out the swirl dams next to the valve right....or someone please tell me im stupid...
jimbo

 

I'm not familiar with the Mustang heads in particular, but a standard procedure as part of a porting job is to unshroud the valves. This involves cutting material from the combustion chamber, which lowers compression. There may also be some poilishing of the combustion chamber, which will also drop it a little.

That's why you really need to get the heads done and get the chambers measured before you buy the pistons or decide on a head gasket.