Pitting in Cylinder head

[ed1le]

I recently purchased my Iroc w/ a blown head gasket (see specs in sig). I'm tearing down the engine and when I took the heads to be pressure tested, they discovered minor pitting around combustion chamber of #8 most likely from detonation. They pressure tested fine and are in real nice shape other than this pitting. Piston appears fine (forged TRW flattops). Prior owner did spray the car a few times w/ a 125 shot and blew a head gasket. The pitting is right around the outer circumference of the chamber (where ring of head gasket is) so I'm wondering if it would prevent the head gasket from properly sealing. I've since removed the nitrous and have it for sale. When he added it, he just installed it and sprayed it, nothing else was done to computer or fuel system to compensate for it or he didn't properly adjust the timing which is what I think was the culprit. Car is running around 5-6lbs. of boost. On a tight budget so trying to get it back together without going crazy for now, don't plan to do any additional mods other than getting it properly tuned.

[GeoffP]

Ed, I think it'll be easier to diagnose if you can take and post a picture of the damaged area. I think it will probably be fine as long as the damage is not on the sealing surface of the head. The pitting could potentially cause hot spots lending to more detonation if you don't smooth it out depending on where exactly the damage is.

[ed1le]

Yeah, I was thinking after I posted that its a tough issue to diagnose, especially w/out pics...probably going to pick them up tomorrow from machine shop and will post pictures of them.

[ed1le]

I picked the heads up yesterday so I could inspect closer. Looks like the pitting is right around the edge of half of the #8 chamber where the headgasket ring is.

[GeoffP]

Is it possible to get a machine shop to weld that in and resurface the head?

[ed1le]

Yes, by the time it's all said and done it'll be about $400 on top of the 168 I spent to have them cleaned & pressure tested b/c they'd need to weld, resurface and recommended a valvejob as well b/c of the heat from the welding. Was hoping to avoid shelling out that money but thinking it's unavoidable.

[GeoffP]

$400 isn't too bad for a full head redo including the repair. I'd say it's money well spent considering how nice it'll be when you get it back together.

[ed1le]

No it's not hateful, I'll have close to $600 into the heads but they are real nice heads...this project is starting to quickly cost more than expected but, don't they always!?!?

[MonzaRacer]

Whoa whoa whoa, why weld it up? Why not just get a minimum deck and reuse them. As welding the heads means a furnace brazing process and honestly the one place I would send them would be to Indy cylinder head, but thats me IF I had to weld them.
Why not just have them squared slightly and look around for different head gaskets.
If you had aluminum heads I would call that brinelling (sp) and its from movement of head in relation to gasket and deck.
Honestly I have access to a block/head decking machine so I use that and can cut as little as 0.003 to 0.005 off at a pass. My choice would be resurface and go.
If they are aluminum heads still mill but you need a proper gasket as the gaskets for steel heads have wrong seal ring, get gaskets made for aluminum heads.
And make sure you got good fasteners.
Good luck.