cam problem???

[h2otboat]

Ill start with the basic engine specs,then the problem.. 460 ford .030 over flat top pistons (11.25) comp. DOVE heads with minor port work mainly to the exhaust,stock valves stock log exhaust,port o sonic intake w/750dp.Here is where the problem starts.The can I originally installed in the engine was a solid flat tappet .564lift intake .582ex duration is 250/256 at .050.With this combo the engine would only turn 4000 rpm.After changing ignition and carbs the same results 4000rpm.Finally I broke down and put lastyears cam back in. Its a hyd flat tappet 560 lift in/ex dur.248 at .050 This cam will turn 5000rpm in the same motor.Why will the smaller less agressive cam turn more rpm.FYI pump is a berk JE with an A imp.Thanks for any input

[h2otboat]

One more thing both cams were degreed in properly....

[bobz]

your old cam has a lower power curve and make more torque at lower rpm. the new cam is just starting to work at 4k and most likely 4500 rpm so you lost horspower in the lower rpm.

[coolchange]

advance your cam timing 4 degrees

[1tricky1]

Too big a cam will bleed off cylinder pressure if you don't have enough compression. 256 @ .050 is a big duration. Those valves were being held open too long with the bigger cam. I believe what happened was your old cam was more compatible to your engine set up. With the other work you've done it sounds to me you could make some gains with bigger valves. That would enhance your head work and cam.