Diode

Does anyone have, or know where I can get, the specs for the original '68 L79 cam? I just bought this car and part of the 'documentation' is a Spec Card from Competition Cams. The manual that I have only gives the lobe lift. The Spec Card shows that this number is different from the original (the Competition Cam lobe lift is .0045 more than the original). Not that it matters much, but I'm curious as to how much the duration, timing and overlap also differs from the factory cam. Thanks folks.

clem zahrobsky

the way GM specs cams there is no way to compare aftermarket to GM cams the specs i have for the 3883986 cam are, dur @.050 214/218, valve timing @ .050 intake -3/37, exhaust 49/-11, lift .461/.480

Diode

I see what you mean. The manual I have only shows "lobe lift" which is .2981/.2981 as compared to the cam I have that is .3026/.3026, which sounds like it has more lift. HOWEVER, you said the lift is .461/.480 which I'm guessing is the same thing as the "gross lift" spec for my cam, and that's .454/.454 which appears to be less!? The duration on mine @ .050 is 218/218 compared to 214/218, so the intake has slightly longer duration. I don't understand the numbers that you gave me at all for the timing. The cam I have is speced at .006 intake open at 28 BTDC, etc. Everything about the timing spec is related to before and after top dead center, so I can't figure out what the numbers that you gave me represent. I'm confused… :crazy:

clem zahrobsky

those cam specs are at .050 lift, intake opens at -3 degrees closes at 37 degrees, exhaust opens at 49 degrees and closes at -11 degrees. this is why it is hard to compare different cam shafts because of the use of different timing pionts. GM posted specs this cam, dur 350/352, lift .461/.480, intake open 56 close 114, exhaust open 110 close 62 but no one seems to know at what lift.