Head reface question

[Nathan M]

What's the max amount which can be taken off the cylinder heads on a 3.2 without running into clearance problems (or any problems!) and how much of a compression ratio increase can I get by doing this? (or is it a stupid question!?!?)

[Nathan M]

any takers?

[kstylianos]

Natahn,

If you provide me your e-mail, I can send you a compression ratio spread sheet. Send me a PM.

You'll need to know your current bore, stroke, head and piston dome volumes, assume a deck height of 1.25mm unless you know what it actually is. You can play around with the numbers and see what changes in head volume (CC) can do to CR. I don't know exactly how much milling will reduce head volume CC....a machine shop can probably figure it out if you provide them the CC's.

[Wayne 962]

In general, it's not wise to flycut your heads to increase compression ratio - at least on a 911 engine. The best way is to use JE pistons, or to stretch the rods. These methods are a bit less destructive to your engine. Once you flycut - that's it -they're done...

-Wayne