There is a tempered hardening ,on the top of the cam lobes. It only goes so deep,then you hit soft metal.Most cam grinders(good ones),can tweak the lobe centers 2 or 3 degrees. Only so much you can do.
He might want to call the guys at Oregon. I talked to them about this same thing. They told me that for some reason, the majority or the Chrysler cores they grind seem to be hardened almost all the way to the core. I was surprised by that, but he was adamant about it, saying they had cut a lot of them in half and inspected them.
