I have a 71 f100 long bed with a 390 and c6 trans, 3.70 gears and 26in tall tires on the back, the engine has been bored .030 over, and has c6ae-y and c6ae-y heads that have been ported and polished, shaved and a 3 angle valve job. I forgot what size cam it has ( built several engines since then numbers kinda ran together) roller rockers, the intake is a 428 police interceptor that has been ported and polished to headers and with the electronic ignition. I've been told that with this setup I only have around 350 hp is this true, and what can I do to make a pretty noticable difference in it

 

Anything you do will pretty much move the power up the rpm scale.

A different intake manifold might yield some power. Books have been written on the subject:

Book Review: The Great FE Intake Comparo by Jay Brown | | BangShift.comBangShift.com

Maybe a single plane tunnel port:

Dove Manufacturing

Or just look through the FE forum and wait for another post from one or more of the guys here who race these motors. Hey, I'd search it out for you but....

A different cam.

A stroker crank out to 445:

Survival FE Engine Kits

 

Assuming you have the oem cam, a cam change would definitely help and advance the position also (since depending on the year, most were retarded 5 degrees for smog reasons).........
Polishing the intakes can actually work against you, by reducing the turbulence, it also reduces the fuel/air mixing.while this is great in racing conditions, it's not the best for street uses.....really need the cam specs.

 

Best I remember don't hold me to it but the cam is a comp 268h

 

"mild..............."

That's a much better cam than stock, but nowhere near the top end of bump stick technology.

Comp has a good site:

COMP Cams: Hydraulic Flat Tappet

Going up the scale, you need to consider what your CR is, and what you can live with cam wise. They spell it out pretty well on the site.

 

That's literally just an RV type cam......not much over stock. The 390 with hydraulic lifters, you can easily go up to a 290 duration, 500 lift cam and it will have a nice idle.............basically, that's the issue you are feeling.

BTW....I would not recommend Comp.............
Comp has by appearance - seems to be a company that has experience more cam lobe failures than most and places the blame on the low ZDDP in the oils. Is it a factor yes, but I highly suspect that they are also using Chinese cam billets & they do not include Parkerizing their cams (Parkerizing is the final step and a crucial step to help break the cam in- a heated acid bath that microscopically etches the metal surface and adds a very thin layer of graphite coating which allows the cam lube to hang onto and penetrate into the cam surface during cam break in) unless you specifically request and pay additional money for it.

Considering the cam has such critical importance to the engines performance and life, to me it makes sense to use a cam grinder who will talk with you directly- even modify the cam grind to fit your needs even better and to address the possibility of cam lobe failure with the new oils. With regards to price...the difference is nil- especially considering its cheap insurance to know exactly who is machining such a critical part for your engine. And remember, advertized lift/duration/lobe separation is just that- advertized and not the specific grind including ramp profile that is used on the cam.

I highly recommend Iskenderian & Crower & Chet Herbert & Lunati...all are family owned, been grinding cams for decades, and both will even re-grind your oem cam if possible- saving you even more $.

 

Beechkid has it right in my opinion on the cam issue. Get the right cam for your particular motor, and she will come alive. I used to own a 67 f100 that was tubbed out with Mickey Thompson 33 x 21" tires, and the 390 I had in it didn't have quite the mode yours has. BUT it was built by my uncle who put a custom cam in it, and I could roast those big tires through drive. I also had almost 11 to 1 compression ratio which didn't hurt.