Originally Posted by m42racer

The choice of H-11/L19/300M for Head studs in this application is not the correct material. Yes, its used in high horsepower application but where the fasteners are replaced every race.

H-11/L19/300M is a tool steel from Carpenter steel on the east coast. Very high quality made for specific uses.
It does give high tensile clamping loads in the 260,000 psi range but it comes with some major downsides. It requires every special manufacturing care. It suffers from hydrogen embrittlement both in manufacturing and in general handling. Extreme care must be taken when handling this material as it suffers from Cyclic failures from a small rust pit or what is known as stress corrosion.

It has to be keep dry at all times and oiled and never exposed to water or moisture.

So if your building an engine with these and its hot and your hands or gloves have any moisture on them, your crating a failure. Sweat will create a rust pit and then cracks appear before complete failure under load.

So to use these in a water cooled engine that heat cycles hot and cold and hopefully doesn't come apart on a regular basis, not the best choice of stuff material. I suspect if any engines out there that have these studs installed will fail at some point. Cannot get around the weakness of the material.

Carpenter sell other high grade steels better suited for Head studs that give the same tensile clamping loads or higher.