airboat502

I have zz502 that now is bored to 4.53.Besides that it is a stock short block with 781 heads (stock) and a performer intake. It has been like this for three years and i have been happy with it but now just want a little more power out of it. I'm guessing with these heads haveing the small valves it might be holding it back alittle. I want to put some alu. heads on and maybe swap the cam out if you think it might help. This motor is on a airboat and i don't want to go over 5800 rpms. I can change the pitch in the prop to limit rpms but just want some more power. Do you think it would be wise to change out the heads.
Thanks
Joe

ezstriper

for the RPM you are turning the 781's are decent heads....some port work will help, how much torque does that thing need ?? some of the smaller runner aftermarket heads and decent intake should work well as well...just keep the runner size down..

1BIGJIM

iTrader: (1)

+2 like said above.

I thought all ZZ502 engines came with Edelbrock Heads.

A 502 should make a light air boat scream

airboat502

the long blocks did come with alu.heads but i just bought a short block and threw on what i had. The more torque i can get the better. It will let me put more pitch in the prop to have more push and run ground easier. Right now it will go anywhere i point it but it's nice to have more power. Thanks for your advice.

Raylar

The camshaft in that engine from GM was just about one of the weakest offerings they ever came out with! It loped real cool for a cool sound, but that engine even with the good aluminum heads only made 500HP from 502 cubic inches, real anemic by good standards.!

You can do wonders to that engine with a good intake and camshaft change, talk to Bob Madera on this forum and he can help you with a cam profile and intake recommendation that will get the real torque and power for your air boat needs.

Best Regards,
Ray @ Raylar

ezstriper

if the guides/seats etc are ok in your 781's and you have some time, port them to gasket size, get a performer RPM air gap run a 750 holley DP look into a good cam, Bob @ marine kinectics can set you strait there..also where do you run the airboat ?? always wanted to ride in one of those things...hopefully will on one of my visits to Fl where my son is stationed in the navy...good luck Rob

airboat502

Right now it has a 770 holley street avenger on it. I do have a rpm maniford for a spare that i can swap. I e-mail bob and just waiting for a reply or call back from him. i live in michigan an run the boat all over but the bst place to take it is saginaw bay. If you come through MI ever i would be happy to take you out on it.
Joe