This is a follow up to the o-ringed block question of last week. I got the head off of Tony's engine last night (500+ ci World block, w/ cast iron Indy heads, 13.6 comp ratio w/ flat top pistons, .050" copper head gasket, block is o-ringed, but the head DOES NOT have a reciever groove), and found that the gasket was indeed leaking coolant into the cyl, at the top of cyl between the two coolant passages. What caught me totally by surprise is WHY the gasket was leaking. After cleaning off the head and putting a straight edge on it, I found that the ENTIRE "closed chambered" portion of the combustion chamber was "sunk" in, extending to the coolant passage. Under the straight edge, I was able to easily slide a .005" feeler gauge, and could have most likely put .008" under there. Upon closer inspection, I was surprised at how thin this portion of the head was. Also, the problem seems to be confined to this one cylinder, the other part of the head is completely flat. (bad cyl is #3, not on the end of the head)
I'm looking for any idea to why this happened? The head will probably need to have close to .010" cut off of it to flatten the surface where the gasket and cooling passages are, even more to flatten the combustion chamber. This portion of the head is so thin now, that I'm concerned that it will happen again, if not blow the combustion chamber out completely.
Has anyone seen this problem before with the cast iron Indy's. Anyone know what would cause this?
Sorry this turned out so long, but I hope that we can fix this and he doesn't lose this engine.

Thanks,
Brian Dunnigan

judging from what u described, sounds like a bad casting. did u compare it with the other head?? (thickness in same area). seeya.

Hopefully Slingshot383 will see this and post some pics of one of his iron heads, large portion of the flat in the chamber basically fell out, not blown out but just broke away. He sent me some pics a while back but can't find them now. Looked like a piece of china, the way it broke. The piece was around .200" thick too. Really strange.

We have seen this happen when the head surface has been cut leaving the head deck very thin.Sonic test those areas and you will find how thick it is ,cutting the deck more will result in the same if not worse issue.

Pictures, I have pictures. No online picture account, so if you want to see a crying shame, send me a private message. I've had the 440-1C heads since 2002, and fortunately run a dry block otherwise when the chamber broke out it would have torn things up in the motor. As it was, it just blew pieces of the quench area into the water jacket, and I was able to get a couple of them when I stripped the motor down.