How much metal can be taken from the surface of a Modular head?

[Gearbanger 101]

Not for the purpose of bumping compression, mind you, but I started working on my PI heads and noticed a few minor nicks in the deck surface that don’t sit well with me. How much can these be decked before they’re junk? I’m told cam timing can be affected if too much is taken off, so what’s my limit?

 

[Gearbanger 101]

C'mon....there's got to be at least one or two smart people lurking around today?

 

[mogs01gt]

I think a standard mill of a few thousands would do it but I would be worried about the valves hitting the pistons if you have aftermarket cams. Also, the timing chains of course.

how bad are the nics? If they near the cylinders or water passages,then I would be worried. If they are on random areas of bare metal, I doubt it would effect anything.

 

[Gearbanger 101]

I've still got stock PI cams, so the piston to valve clearance doesn't worry me much, but one of the scuffs is right around the O-ring seal of the head gasket. That's the one that concerns me a little If it comes right down to it and I can't take much off, I'm just going to smooth it out with a little JB Weld and see what happens. I'm running elevated cylinder pressures through them because of my blower and the last thing I want is to have to replace a head gasket after getting them all together. But I also don't want to have to junk the head if I don't need to either!

 

[mogs01gt]

How did you get a nic there?Yes, I would be concern about gasket seal if I had a nic there.

 

[Superhereaux]

i don't think you can't mill the head for any reason


at least that's what my ford instructor told me

 

[Gearbanger 101]

How did you get a nic there?

I'm not sure? These heads are so friggin fragile. I noticed they got the crap beat out of them in shipping, so it might have happend then? I didn't really start to look them over until I decided to start the port work on them. The slightest little ding makes a mark in them. Damn aluminum!!!

 

[DBMSTNG]

remove .010" or less.