If I have a low compression 72 motor and I want more compression. Can I just have the heads shaved/surfaced and put them back on? I have a cam installed that may prefer more compression to really boogie. How much should be removed? Do I have to do anything to the intake, or just get some weird intake gaskets? Thanx all.
For every .010, you would gain about .20 on your compression. I did this on Desktop Dyno with a .030 over bore and 24 cc pistons and 72 cc heads and a .040 gasket. Phil no shaving of heads 8.0 shaved .010 8.2 shaved .020 8.38 shaved .030 8.56 etc, etc, etc. They do make thinner head gaskets, but I believe those are for more of a race motor. But a .020 head gasket would help about .38 or so.
Don't forget as you shave the head they move closer together so you need to either take some off the intake face side or get some TA gaskets and test fit them before final assembly and make sure things line up. later Tim
Yo The motor is a stock rebuild, I want to go as high as I can for 91 (CA gas) octane. I do not know if the block/heads were surfaced (so how much) on the rebuild. I am assuming I should take off around .100 off, but I don't want to remove material from the intake, then the intake might not carry over to the kick asprin motor I want to build some day. Do I have to check piston to deck height & chamber size to do this right? I guess to check piston height, you just measure from the top of the piston edge to the deck (right?). Then have the machine shop do the chambers? Unless it might be safe to just take off .100 & bolt them back on. Thanx for your help. Any more input appreciated.
IMO, I wouldn't remove this much (.100) from the cyl. head. That might weaken the head and lead to cracking. Get some good forged pistons, mill the block decks to get from .002 - .005, polish the piston tops and combustion chambers in the heads. If the block decks are milled alot or the cylinder heads, you might want to have some milled off of the intake side of the heads. Otherwise the intake will not lay into the Vee squarely, and you'll have vacuum leaks around the bottom of the ports. There is a formula for converting how much to remove from the intake side vs. what was removed from the deck side. I don't remember for sure, nor can I find it right now, but I'm sure someone around here has it memorized. Of course you can do this to the intake also instead of the head, but in my opinion, its better to leave the intake stock, so that it works on any engine.
