Well I’ve looked through some searches and it seems to be agreed that the stock combustion chambers are 58cc on a 95 LT1. My short story, I wipe three main and two rod bearings so I’m building a 383. The guy doing the porting job is going to open the chambers around the valves, like many before me have done. What I have not found is how much to mill off for X amount of cc’s. ex. If the new chamber size is 64cc how much do I mill to get it back to 58cc’s or 54cc’s? I have forged pistons going in that would bring the compression to 10.4 on stock heads.

Thanks!

 

The best thing to do is cut the head to 62CC's (.010=1CC) "0" deck the block and get a set af 2 eyebrow pistons(4CC's) and ya will have in the area of 11.5-1.
Ya can get a set of dome pistons and have them cut down to 4CC's and come out with about 12.8.

If ya cut the head much ya run into intake and port alignment problem's and have to redo the intake.
If they are stock castings the deck will be very thin or no deck at all, if cut back to 54CC's which is stock on the few set's I have measured.