[unclebilly]

I doubt it is kovar given that kovar has a very low thermal expansion and the thermal expansion of the studs must roughly match the material of the cylinder and head to ensure consistent clamping force of the gaskets during the thermal cycling of the engine during operation.

My first patent was for a thermal clamping mechanism for a solid oxide fuel cell stack. In many ways, the system is very similar to the head studs on a 911...