Help Legal Issue Snapped Cam...

[The Pupat]

Doesn't the process involve building up the profile by welding, and then machining back to suit? In which case the heat cycling is an unavoidable part of the process.

If that were the case you can usually anneal the hardness out of the steel and re Heat Treat them to bring it back up how it should be.

[lukevl]

Browny has it. The lobes are ground down and then welded up using stellite (spelling) and finish ground again. The stellite is very hard and quite sensitive to cracking. It would not be capable of a second heat treatment because through hardening and case hardening would not work. But hardness is not the problem, its the fact that two dissimalar metals are joined together and the contact material is not porous like iron so does not self-lubricate with carbides and oil retention.
As far as I know the only cams that are case hardended are the american rollers. These can be distinguished by the copper colour on the shaft. I feel this is not the ideal way to do the job. Either chill-cast lobes on an iron cam or through hardening (induction for example) on a cast iron cam.

With the Honda cams in question, for $1500 it sounds like they aren't hard-faced anyway especially considering he has been told they are 'manufactured'. Did they have adjustable gears on them? If so this may make the nose snapping more prominant due to the bolt not screwign in as far as a standard cam. I bet if you look in the factory manual the torque spec would be moderate and most likely have a warning about over-tightening.