I had to switch out cams in my 79 Aspen which had the motor out of a 80 Aspen with around 30k orignal miles on it when my new oil pump decided it wasnt going to spin and would rather snap the gear in half and take out the teeth on the drive gear on my cam. Well anyhow I pulled the cam out of the 79's orignal motor which had 70k orignal miles on it to replace the busted one in the car. Wow both cams have some serious grooves on the lobe that drives the fuel pumps. The fuel pump drive arm was wore bad too. Whats up with this? Common? Not very impressive if it is.

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This problem is getting more common now that all the good anti-friction additives are being removed from engine oil. (search ZDDP or EOS)

Most cam grinders you talk to will say that the cause of this problem is dirty engine oil and this is one area that get's worn first when owners do not follow recommended oil change intervals.

One thing I do when rebuilding a SL6 is to drill an extra oil drain back hole in the lifter gallery so return oil from the rocker arms spills right onto the fuel pump lobe.
DD