Head warpage tolerance

[JAMMAN]

Finally heads are off and after I cleaned them up I used a straight edge (I'm a machinist this is not an ordinary straight edge) and I found an even consistent bow in the heads about .005" on one head and almost .007" on the other, dead in the middle of the head.

If this were one of my machines at work looking at it as a big chunk of machined cast aluminum, I would expect bow and would torque it from the inside out but I have read specs from "experts" and the expectations are all over the map. One site actually says no more then .0015 warp is tolerated. I know for a fact even on the best mikron or mori you cannot get a piece of aluminum of any variety that large that flat no matter how you machine it. Maybe 2 sided tape on a blanchard grinder then the first time you tighten it it warps when you loosen it.

Are there any precision style gear heads here that have experience with heads? These things look good and were probably never overheated. The head gasket section that failed was between 2 and 4 AND favored 2 being it was full of glycol, no where near the maximum gap in the middle I measured on the bench.

OH and I'm not rich by the way or the crate would have already been ordered I like this guy:

 

[05daytona]

I look at it this way, that gasket failed for a reason. If it were me, I'd have them milled.

 

[JAMMAN]

Heads are done, don't know the cost yet. I can't pick them up today but will tomorrow. Putting it together this weekend.

Milled the exhaust manifolds myself, they were warped about .05 with the two middle outlets touching the plate and the two outside ones with a huge gap. No wonder the thing had an exhaust leak.

Going to be a different truck altogether when I fire it up.

 

[JAMMAN]

Well 100 bucks later the heads are flat.

It wasn't burning oil but I do have a set of seals I got with the gasket ensemble so I might just go for it.

 

[Dubstep Shep]

Have you checked the surface roughness of the heads and engine block?

On multiple occasions I've seen head gasket failures when the roughness was incorrect for the head gasket. Too smooth and the gasket won't grip, too rough and you have leaks. You also have to consider the thickness of the gasket when compressed, the torque and clamp load on your head bolts.

If all that lines up you should be problem free.