snk-huntr

iTrader: (2)

does having my heads milled up the compression any?

old93camaro

iTrader: (8)

yea but head gasket helps as well

Vettestir

Yes but very little unless you take .03 or more off. It's best to take a light clean up maybe .005 to .010 off then run a thinner head gasket.

Gojira94

iTrader: (4)

Definitely... milling off more than .010 is probably not a good idea for a street setup

Here's a good article that talks about the procceses available:

http://www.aa1car.com/library/ar996.htm

Also look at how deck height affects compression. And piston shape, pin height, head gasket thickness, etc. etc.

Why do you ask?

Wicked94Z

iTrader: (26)

lets think about this... you're milling the head, aka removing material to make the combustion chamber smaller. Yes that raises your CR.

snk-huntr

iTrader: (2)

I had 2 cracked heads and they were milled enough to where they knicked a valve on one head

Gojira94

iTrader: (4)

Oooouuch... must have taken a lot off. Did they tell you how much they had to take off? A thicker head gasket might have made the difference. Checking clearance with some clay is usually a good idea when you think you're going to be close. Different pistons is usually one way to solve it. I don't know if you can or should try to relieve the pistons' valve relief any more than they are, though I bet it's been done before...

GIZMO

iTrader: (8)

Who mills heads with the valves still in them?

snk-huntr

iTrader: (2)

didnt ask how much he took off , this was done last year and the car runs good just wondering if this helped or hurt power , mods are in sig , car runs 8.1 on motor and 7.30 on a 75 shot and my buddies keep thinking I have more done to it than what I say, haters ,lol

Gojira94

iTrader: (4)

x2... Just re-read and realized what was said. Well, I'd not be too happy about it, but if it's not creating a problem right now, I'd leave and start with different heads next time around. And use somebody else next time for the porting...

IronOutlaw

iTrader: (4)

My old formulas heads were milled .080

had to "modify" the intake Manifold to get it to go back on. I had to run 93 in the car because it would diesal and spark knock with anything less.

jay7199

iTrader: (9)

uhhh i wouldn't run anything less then 93 in any of my cars

Puck

iTrader: (17)

My AFRs are getting .042 milled down, have huge valves, and are going on a zero decked block with a big, high lift cam.

I'm curious to the PTV I'll have .

Milling more then .010 on an SBC is not dangerous. You should always check PTV anyway...

BTW, each .005-.006 is around one cc drop in chamber size. You can only flat mill down around .050 before seriously screwing up your intake seal, but you can angle mill farther then that.

old93camaro

iTrader: (8)

if you dont know how far they have been milled usually and i mean usually they stamp what they did on the head