Cam Shaft questions

[Steve welder]

Two Questions
A cam with bad lobes, exactly how would one come to that evaluation? Years back I had wiped lobes on a cam in a 305 Chevy, which at the time had a reputation for wiping lobes. The truck had no power, ran rough and spit back the through carb......After checking ignition and fuel a mechanic mentioned the cam, which as it turns out was the problem
Few weeks ago a guy I know pulls up at the cruise in, has a 65 GTO with 389 engine. Engine is running lousy, guy there pulls spark plug wire one at a time and it sounds like it wasn't or hardly firing on 3 cylinders
Turns out the guy was oil not recommended for old cars and the cam had several bad lobes
My other question is how a camshaft lift/ duration affects engine vacuum.
Thanks

 

[Syleng1]

Yes - flat tappet cams need lots of zinc in the oil that new oil does not have for the sake of a greener world. (Cough- bscough)
Lack of zinc will wipe out a cam or slowly wear them all out. Dial indicator on top of rocker tips is easy way to test how much throw each rocker is moving. You also could have a bad lifter (collapsed) causing the same thing. That could just be a worn out part.

 

[George Jets]

Here is a flat lobe cam.

Turned it into a new cam bearing fitting cam.

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