Ric232

CP Performance is advertising a custom ground Comp Cam for these motors. They say:

"This is an incredible camshaft for your late model 454/502 Magnum EFI engine; big power yet still EFI compatible."

The profile is:

223int/230exh duration; .575int/.566exh lift (seems strange); 114deg LSA

Anyone EFI experts out there have an opinion on this one?

Dennis Moore

I think it sounds like a good camshaft. The wide lobe sep angle is throwing away 20 horsepower but it may be needed to keep the computer calibrated to the engine.

Pretty hard to make more power without making the fuel curve richer (fuel rail pressure increase or ECM recalibration). More air into the engine (with a more efficient camshaft) also means it needs more fuel into the engine!

If a marine engine had an oxygen sensor the ECM would recalibrate itself for the increase in air flow by increasing the fuel flow. A marine engine is stuck on a preprogramed fuel curve.

Sincerely
Dennis Moore

JohnnyM

Dennis Isn't this cam considerably larger than the 515/520 you suggested in your book? I have gen 5 502's with carbs in an old 35 Cigarette(12,000#)with bravo ones. What cams would You suggest for this application.I am more concerned with fuel economy then top mph as I use the boat for diving 30 plus miles offshore on the westcoast of Florida. I already planned on switching to quadrajets for economy as per your suggestion in another thread. Thanks Johnny

JohnnyM

Ric Is that Comp Cams cam a roller or flat tappet? Johnny

Ric232

Johnny M., it is supposed to be a roller hydraulic cam.

Dennis, you always seem to appear at the best times. I just thought it was strange that the exhaust lift was lower than the intake lift.

When I called Comp Cams directly, they recommended a cam with 218/224 duration; 510/510 lift; 112 LSA (vs 110 due to water reversion issues). This seems drastically different from CP Performance's Comp Cam (223/230 duration; 575/566 lift; 114 LSA). I don't know enough about cam profiles to know what the performance difference might be between these two cams (except for the difference in LSA). Dennis, can you educate me on how these two cams might perform differently (ignoring the ECU issue for a moment).

Thanks.

JohnnyM

Ric The 515/520 CC is the largest hydraulic flat tappet recommended by Dennis in his book. Johnny

Ric232

Not exactly. He recommends larger cams if you are willing to change valve springs. I have his book and know it well.

JohnnyM

Ric are You sure he recommends larger flat tappet(NOT ROLLER)camshafts? I might be wrong. Sorry if I am. I will check the book.

Ric232

Johnny, sorry, I did not realize you were referring to flat tappet. Mine is roller, so that is what I've been referring to all along.