502 heads on 454 mpi?
 

A friend of mine has a pair of 502 rectangle port heads that i can get cheap. right now i have a 96 7.4 mpi with the 502 intake(for looks) any way i have the oval port heads and want to swap out to the rectangle port heads. what difference will i see? will i need my computer remaped for the increased rpm range? whats the good and bad?
jay

Oh boy, there is a little more to it that swaping heads. The heads you have are about 100cc with dish pistons, the rec heads are 118cc with a slight dome. It would be a complete mismatch.
I assume you have the 310 HP L29 Vortec engine. The 385 HP Mag already has rec port heads.

i have a 96 motor 330hp, flat top pistons 8.1 to 1 compression. i thought my heads were also around 118cc.

The ecm will definitely need to be reprogrammed.
Eddie

Eddie will i have any problems just swapping out to these heads after a reprogram? what should i expect to gain?
thanks

Is it a Gen 5 or 6 ? Gen 5 has small oval port heads with 118cc chambers. Gen 6 has vortec large oval port heads with 100cc chambers.

seems like you'll lose torque & hp through most of your RPM range atleast till 4500 w/ the rec port heads. I would port your Vortecs or stay w/ large ovals on a 454. The guy who ported & flowed my vortecs said they should support up to 550hp.

it has the small oval with the 118cc. so from my understanding because f my cam being small i really wont make power improvements? so can some one reccomend a valve train upgrade to match or should i just contact rmbuilder i have read alot about? im not looking to go over board, just want to beef up some power out of the mpi. can i use the 500hp efi cam?
thanks jay

The same guy mentioned above put a mild cam (224/224 .500") in a stock low compression 454 w/ non ported peanut heads & it dynoed approximately 420hp / 530tq. I don’t remember if it was a roller or flat tappet, probably roller.

You must have a Gen 5 engine. That is what I started with. Problem is you have all cast internals, small port heads, small cam, restrictive exhaust. Be prepaired to spend 10K to get any power out of that engine. Here is what I did to get 500HP. Bored and stroked to 489 with forged internals, EMI exhaust/long risers, Holley MPI kit, RMbuilder Cam & valvetrain, large oval port heads, oil system upgrade. That is just what I remember off the top of my head. I spent way more than 10K just on parts. I did most of my upgrades one part at a time and I do all my own wrench work. I would recomend you get the exhaust first, It is a bolt on part and you will need it later for the cam upgrade. Do not expect a big speed gain, 1 or 2 MPH max.