[Glenn Sedig]

The heat generated by 2 exhaust valves side by side in the center of the head softens the alum enough to cause the web between the center cylinders to deform down .002 to .004. The ridges in the head gasket also indent into the alum web by several thousands of an inch. The other webs with 2 intake valves side by side show no distortion or effects from heat. After the center web is pushed down, the head gasket has less clamping pressure in that area, which slows the disipation of heat causing the head gasket to burn and allows combustion pressure to pass between the cylinders.

All of the heads I have put inserts into regardless of the brand have had this same problem.

On my engine with over 15:1 compression I have had no problems. When tearing it down, the area of the gasket where the insert is, shows no sign of heat or leakage. The insert is pulling the heat away from the area so that the insert in the web does not get hot enough to deform. The copper alloy insert will also take much more heat that is generated in the web area before it gets soft enough to deform.

Jim is right, the problem is too much heat. So the answer is to get rid of some of the heat or find something that will hold up to the heat. Adding water holes will get rid of some off the heat and the copper inserts will hold up to the heat.

One or both of the fixes can be a solution. With that said we will still have problems in the center web area on high hp heads because of the heat and the thickness of the web.