[Healeys] Cam wear question

[Bob Spidell]

The cam we just pulled out of my BJ8 showed considerable wear, even 
though I'd changed the oil regularly (I did get almost 120K on it).  I 
can see how a roller cam would suffer less wear since there could be 
considerably less friction on the lobes, but don't see why OHC cams 
don't suffer similar wear since they apply similar pressure--minus the 
lifter and pushrod weight--on either followers or the valves directly.  
What am I missing?

Bob