: Polishing Cam lobes?



IXSLR8
09-10-11, 09:26 PM
I just started into another Northstar engine, a 1996 Deville Concourse Vin 9 engine. Mileage is approximately 150K.

I have the intake manifold and valve covers off getting ready to replace the head gaskets just for future insurance.

I noticed that the cams have worn into some of the lifters and have left round score marks. The cams seem to be worn on the opposite sides of the pointed lobes (the rounded part). There appears to be some scoring or roughness on the surfaces there but not all the way round to the pointed lobes. To be specific, I'm not talking about the journals that the cam caps secure the cams in place with. Just the lobe part of the cam that push on the lifters and open the valves.

Is there a way to polish the back side of the cam lobes? The only Northstar cam areas that I've polished before were the journals on a lathe. Can a machine shop polish the opposite side of the lobes? Is this commonly done on our engines? Sorry I don't have pics to show you veterans. I don't know what is normal since my other northstar engine only has 51K on it.

Perhaps the previous owner didn't use high zinc oil, eh!

Submariner409
09-11-11, 12:25 PM
Lifter faces and cam lobes are surface hardened. Once a lifter or lobe is scored, it's replacement time. Or you might talk to CHRFAB about a regrind.