Man,the only cam failure I ever experienced happened within the first hour ,and it wasv totally my fault up on tear down, what happened was on my big block I decided I needed screens in all the drain back holes (over the cam in the block} got over zealous with the epoxy and wasn't lubing the cam lobes,It's very rare for a cam to fail for no good reason. But of course Chevy proved that theory wrong back in the early eighties with their 305 ? or was it the 307 ?