Thinking about upgrading my 502's 425hp carbed, gm performance based, holly marine carbs (800) and stainless marine exhaust. Im thinking right now I want to get around 575hp, change heads/cam/intake, and want to run on 87 octane. Anyone got a good similar setup they have already done or reccomend a good head/cam/intake combination

easy..... call rmbuilder 585-654-8583

Bob Mandra

Use your heads, Crane 741 roller cam, Roller rockers, dart single plane intake, holley 800 carb. Probably be right at your goal, or close to it!

Will the 800CFM be enough for 502's running the 741?
I'm running an 850 and building a similar setup.

Are you running the TBIV ignition?

Plenty of carb for them.

I sent you a pm. Call me.

I don't know if you're running a blower, but could you put a set of rectangle port closed chamber heads from a 69-71 BBC to bump up the compression to gain some more power?

AFR 265 oval heads, Vic Junior intake, RM Builder cam and valvetrain. Easy 600+hp. An 800cfm carb is just barely big enough for this app and would need a bit of tweaking to optimize. A 950ish works better. I did a pair in a 29 Baja upgraded from 502Mag MPI. It went from 68 before to 86mph after! They made 630hp 605torque. Bob's the man!

You should have the square port heads i believe. Of course their are better choices for heads out there, but if your on a budget yours can work to meet your goal. I highly recommend sending your heads to Jimmy Valayko in grand rapids for a little magic, bob madeira cam, and you'll be a happy guy. Adding a solid 100-125HP per side in your 28 should make you grin.