Compression

[Bobs68]

Can anyone give me a ballpark compression number for me? It's a 200 with stock pistons, stock deck height, a 250 head with .060 milled off. Right now I have a stock cam. If I mill .010 off what will that improve it too? When I rebuild I will 0 deck the block and install flat tops but just wondering what it is now.

Bob

 

[CZLN6]

Howdy Bob:

What head gasket are you using?

adios, David

 

[Bobs68]

Hi David, Thanks for the reply, I'm using a Felpro gasket.

 

[CZLN6]

Howdy Back Bob:

Assuming an unmolested 250 head (Casting code would be more exact) with 62 cc chambers a .060" Mill cut would reduce chamber volumes by approximately 12 ccs. The new CR would be approximately 8.7:1. Another .010" reduction, all else being static, would result in CR of 8.9:1. These figures are estimates based on previous experiences with these materials.

If you're planning to zero deck the block in the future, you may not want to mill anymore off the head for now. You might want to click onto our website and play with the compression calculator.

Adios, David

 

[Bobs68]

Thanks David, I appreciate your expertise. It seems like zero decking the block and using flat top pistons will put me at about 10.6 to 1. Your right, I don't want to mill any further.

Bob