I recently overheated my engine causing water to get into the oil. Upon taking everything apart the heads were warped and had to be milled 0.015''. The gaskets that were on there were Fel Pro 1074 and did not have any damage to them. I'm going to buy a new set and for less than half of what Cometic's cost I was thinking I'd get another set of FP's. I spray a 175 shot every now and then and was really impressed with how the FP's didn't blow under that heat. I want to stay with something in the 0.039'' range and not thinner because of what had to be milled off the heads.

 

Did you have the heads checked for hardness? That bad an overheating can soften them and they may not hold gaskets anymore.

 

I did not. I'm getting a valve job now since they're off so I'll ask them to check that. What are my options if they won't hold a gasket? Call AI for new heads?

 

16-18psi + nitrous with 1074's.

Rich

 

1074's are for a 4.125 bore. Is yours really punched out that far?

Assuming you were shaved down .015. Wouldn't you want a slightly larger compressed height so as to not up the compression too far?

Have you checked what the new compression would be with the same gasket and .015?

 

Mine is a stock bore and I thought that was much but it's also what was on there and worked fine. I haven't checked the compression with the same gasket and 0.015'' milled off the heads. I run 4-valve reliefs pistons and a CC306 cam so I'm not thinking it will have clearance problems. Maybe someone else could offer some insight to this.

 

Head gaskets have a larger bore than the block they are sealing a head too

 

F that, I wouldn't go out that far. I'de know what my compression was going to be before I did it too.

 

If I recall correctly....the 1074 has the same diameter hole as a stock gasket. I remember seeing the difference between the gasket and the bore when changing mine(I got concerned on this too....). I still had the stockers and checked them....same measurement....but you need to double check me on it.

My heads have been milled too and I have had no issues(I think mine were milled around 0.010").

 

I believe most gaskets you will find will have a 4.100-4.110 bore for the LT1. Yes you can get something like a Cometic with a 4.040 bore. I am guessing the normal gaskets have a large bore for a couple reasons, one to keep the gasket away from the torture of the combustion chamber and two so they don't have to be so precise, look at most of them and they are not even truly round.

If the heads are soft yeah a set of AI heads would be great but it would suck to have to throw away what you have seeing as it does already work well. Maybe talk to someone like Cometic and see if their gaskets could help seal a soft head.

Or maybe you could sell them to someone staying purely NA and see if a particular gasket can help seal them.

I know when you send heads to AI one of the first things they do is check hardness, because if the casting has lost integrity no sense in putting the work into it.