[darbikrash]

Originally Posted by 1968GTO421

".When you nitride a cast iron cam, the process reduces the core hardness of the material. You end up with a very hard, but thin outer layer, but the backing material is now much softer. The hard shell. helps with break-in, but the after a while the softer backing material gives way, and the hard shell starts to flake off. As soon as that starts, your cam is toast."

I’ve read this numerous times on Speedtalk and it’s always from the same guy- a cam grinder- who ought to know better.

A properly nitrided cam, meaning of the correct case depth and hardness for the contact stresses anticipated will not suffer an adhesion failure due to a “soft core”. Plasma (or Ion) nitriding was designed specifically to withstand high impact loads, and it was originally developed for use in hot forging dies which receive hundreds of tons of impact force and do not suffer abnormal wear or any delamination after years of service.

Regarding the combination of DLC lifters and nitrided cams, the general rule about running hardened surfaces against each other is that they should not be at or near the same hardness, but rather at least 6-9 Rockwell C difference, and the more the better.

Typically nitriding a cam gives you 58-63 Rc, DLC is much higher, close to 100 Rc.