I do NOT think it is the cam which is the problem. I think you could make more overall power with a more mild cam, but if the cam were the problem, your low end would be more of the problem.
I think it is most likley a fuel issue. Definatly put in a better than stock fuel pump, because the stock fuel pump is the weakest part of the fuel system. The ADFP regulator will be a good tuning tool. I work in a shop and many times when a vehicle comes in with a "sluggish acceleration" issue, a weak fuel pump is many times to blame, especailly when it's a top end problem. Your fuel pump might not be on the way out, however it could, but if it can't maintain fuel flow and keep pressure, your going to have problems.
Valve springs not being strong enough to handle that kind of lift as speed will cause valve float and definatly kill power. Who knows about the springs you have, maby upgraded, but maby not upgraded enough. Valve float can usually be heard as well as felt.
Also, Ignition, what plugs, thier condition, and where are they gapped? How about the cap, rotor, wires? It could be possible that the spark is being "blown out" at higher rpm's.
When I was 18 I had a 76 Firebird with a small Block chevy in it.I didnt know about combo's,I got a Target Master 350=4-bolt main with about 200hp.I kept on the stock heads,put on a Edlebrock terancharla intake,,850DP Holley,,,LOL,,and bought a cam off a guy.A solid cam for his old motor that had 12:1 comp and 488 gears!! Talk about TOO MUCH CAM!!!! This thing sounded so retarded(I mean Stupid) It only had power from 4500rpm to 6500,and thats it!! I wound up spinning a bearing So yes,,,too much cam is a bad thing
UPDATE 10/31/04: OK...the following was done: Changed to a 255lph fuel pump...the car had a stock 95lph fuel pump. Set the fuel pressure at 40psi with the vacuum on about 46-48psi with vacuum off...is this right? I have 24# injectors...Set the TPS at .98 volts...Set the timing at 16* over the 14* I had before...The car feels better overall feels better but still falls flat on its face at 5100RPM...I will change the valve springs next week with ones that have higher spring pressure...I think FORD RACING makes a set for the 351 that has a 130+ spring pressure...The cam at straight up has a 4-5* retard...so it is retared 4-5* at straight up...this means the car should pull up top right? Any other ideas or suggestions would be helpful...thanks...
Do NOT guess on the spring pressures for the cam. PLEASE call Summit or trick flow to find out the spring requirments.
Not only can using the wrong valve springs cause valve float but with the wrong installed hiegth they can also cause coil bind & really screw your valvetrain
Like said above if you dunno about the fuel pump it could be that. However I would get an FP gauge and see how your FP changes as yu rev the motor. At WOT your Fp should go up about 5 psi or so. If it doesnt go up that much or worse, if it drops, then you know your running into fuel starvation. Honestly I wouldent waste money on a Fuel pump unless you know that thats the problem.
Oh and about the cam being too big....its way too big. I run a comp cams extreme energy 218/224 duration @ .050 w/ .544" lift on both lobes and 112 LSA and check my setup in my sig. I mean its a bit small (for my setup) but it works good for me. Just to give you an idea....
Also, if your springs arent good enough valve float could be a problem with that much lift...as mentioned before.
my guess is you're floating the valves.
let us know what springs do for you.
typiclly retarding the cam moves the power band up, and advancing moves it down... that's the theory anyways.
stock iron gt40's flow 180... ported, they can go up handy 230, and, that is not too much cam for the combo in my opinion.
I don't think it's the perfect cam for the combo with the exhaust bias... Buddy Rawls has stated that the ford iron heads do not need an exhaust biased cam, and from all the customs I've seen him grind for ford iron heads, non have had the exhaust bias.