I want to reduce my combustion chamber by 5 cc's

[Nasty Wendy]

Can the heads be milled enough to accomplish this and not have problems with intake fitment? Anybody know how much I'll have to have shaved off to accomplish this? Thanks.

 

[Big Turbo Scott]

Head Decking

Hey Wendy, I know that to reduce a 40 cc chamber by 1cc you need to remove .006 of material. I also know that most buick iron heads have a .250 deck and a 46cc chamber. Too remove a cc from a 46cc chamber might be .0055 or .005 or less. I personally would not go below a .200 deck on the heads. I understand the benefits of a smaller chamber but I believe a better route to go would be to mill the deck of the block to a "zero" deck. Not sure how far your pistons are in the hole but a zero deck offers several benefits and is a viable option. Also, If you insist on cutting the heads, .010 is all that I would go. Remember that you still might have intake fitment issues and that your pushrod length will have to be rechecked.

I would go about it this way. Cut .010 from your heads AND block then call a reputable valve manufacturer and order a set of flat face valves. Remember to check your pushrods too. That should get you pretty close. Also, you may be able to find a thinner gasket than .060 to futher aid you with out any issues with the manifold. My block and heads have been decked .010 each and the manifold fits fine. Im also using Cometics MLS. Hope this helps!

BTS

 

[SPOOLFOOL2]

The RJC head gasket is a bit thiner than most and may get you where you want to be. They work great too.


Good luck
Mike B.

 

[Nasty Wendy]

Hey Wendy, I know that to reduce a 40 cc chamber by 1cc you need to remove .006 of material. I also know that most buick iron heads have a .250 deck and a 46cc chamber. Too remove a cc from a 46cc chamber might be .0055 or .005 or less.
BTS

Good info. Thanks.

 

[Nasty Wendy]

RJC gaskets won't work for me. Its a 4.1. Cometic gaskets are available in a .027 thickness and I'm still gonna need a 41cc combustion chamber using those.