[Formulas]

Cams back in early 80s late 70s were showing up with both size lobes..

I noticed the difference back then but nobody seemed to care or talk about it..

My old HO .. HC-03 cam is a fatty and my Comp AH294-8

[Jay S]

For stock cams like a 066 or 068 I do not think the lobe width will make any difference in longevity. On stock type cams I think the narrower lobe is easier to break in, and the lifter machining doesn’t have to be quite as perfect. Some of the original factory Pontiac stock cams were ground on the narrower lobes, they were not all wide lobes. On bigger cams where the profile is using more of the lifter face the lobe width is a lot more important. A big profile on a narrow lobe there ends up with less footprint where the lifter has the highest acceleration. That is why most mechanical cams use the wider lobes and the EPC cores are EP-2 instead of the standard cores. What I have seen on the narrower lobes and bigger profiles is the lifter digs into the base circle the closing side of the base circle, and the taper gets removed quicker on the opening ramp.

Comp cams and generally uses narrower cam cores from EPC. Crower uses the narrow lobes also. The letter EP-1 or EP should be cast into on the core somewhere between the lobes on EPC cores. Melling always uses CMC cores and has a little wider lobes with the letters CWC cast into the core. Both EPC and CMC cores are cast at CWC though.

[Jay S]

A while back I helped a guy that said he had a 068 copy. But when I asked, I found out he was using comp cams XE profiles that had about the same .050” durations as a stock 068. He duplicated the ICL and LSA of an 068, but with XE profiles on both the intake and exhaust. It ran ok, but it would not have out ran an original 068 that had less a lot less lift. I think his XE cam made it about 40,000 miles before he lost the cam and beat the valve guide to the point it was using a lot of oil. It appeared to have a lot of reversion issues at high RPM’s, the power just abruptly nosed over when he put it on a wheel dyno.

With cams, the term copy can be a pretty vague term.

[geeteeohguy]

Originally Posted by Formulas

Cams back in early 80s late 70s were showing up with both size lobes..

I noticed the difference back then but nobody seemed to care or talk about it..

My old HO .. HC-03 cam is a fatty and my Comp AH294-8

Probably because cams and lifters worked 99% of the time back then. I never had a failure, and didn't know anybody who had one, personally.

Catastrophic cam and lifter failure is a 21st century phenomenon.

[242177P]

Originally Posted by geeteeohguy

Catastrophic cam and lifter failure is a 21st century phenomenon.

Not entirely true. Chebbies in the '80s ate a bunch of
cams. Neighbor dropped a lifter into the oil pan, LOL.
But I never had trouble with Pontiac cams (including
a used one) in the before times.