Boatally Insane

iTrader: (1)

I'm currently rebuilding a 1995 502 mag efi for my boat and would appreciate any input on things I should do differently or something I might have missed. So here is what I've come up with so far.


It's a Gen VI block bored .030 over. J & E flat top pistons. Block "parallel" decked (just enough to make sure it's straight). The crank is turned .010 - .010. Stock rods. Balanced rotating assembly. Surface the heads. Manley Severe duty 2.25 intake and 1.90 inconel exhaust valves. Some mild porting. ARP head bolts and rocker studs. Crane gold roller rockers. Cometic head gaskets. Crane roller cam. Lift .576 in .598 ex Duration 222 in 230 ex 114 lobe separation (grind #HR-222/339-2S-14 IG) Intake runners shortened and shaped.(but not extrude honed like the AZ Speed intake) Revolution Marine exhaust manifolds. Corsa "captain's call" exhaust. Mefi 3 Computer programmed by Mark at precision. (my harness has already been re-pinned for it) Stock ignition with an MSD replacement coil.


Originally I was going to rebuild the engine basically stock and put a Vortech supercharger on it but I just couldn't quite afford the blower kit this year. I wanted to keep that as a possible option for next year so I am keeping the compression ratio near stock.

Can I go any bigger on the cam and still keep the selectable exhaust or am I pushing it already?
Will the VST fuel system be able to keep up?
Are there any decent full-time mufflers reasonably priced?
What lifters should I use?



Any input would be greatly appreciated.

Doug

mcollinstn

use ARP rod bolts, and have the big ends resized.

your cam choice is fine.
I'd use the longer Crane stock replacements that locate with the GM dogbone key plate. No link plate to give you troubles.

Boatally Insane

iTrader: (1)

Any thoughts on the VST system?


Doug

kennywould

I scrapped mine, remodeled the fuel rail to take 8-an lines in and out, electric fuel pump before, thru the fuel rail, thru a regulator, return line to the tank. I had problems with that system cooking my fuel, motor would diesel when you went to shut it down, they added the cool fuel sytem in later models, I don't know which one you have. Mine was 1996 model, gen v. Weldon makes some nice pumps and regulators, remodel the fuel rail, thats a project!

GPM

I would be looking at a 231/ [email protected] with a 110 lobe separation for better bottom and mid range. If your oil pump drive rod has a nylon collar throw it away. The gen 6 motor has a 6 bolt timing cover, just incase you're not sure what you have. Look at GGB.ca for mufflers.

Boatally Insane

iTrader: (1)

Wouldn't that cam cause reversion with my short risers and Captain's call exhaust?

My block is a Gen VI with a 6 bolt timing cover but the dress is 1995 Gen V without the fuel cooler.
Any idea why the factory fuel injection systems do not return to the tank?
I do have an extra fitting in my tank that is plugged.

I seem to remember Dustin Whipple saying something to the effect that it's not coast guard approved to return it to the tank which is why they return it to the suction side of the pump in their systems.

Thanks for all the good ideas so far,


Doug

GPM

I ran the 231/239 in a 454, great low and midrange torque, had the captains call, no problems at all. My opinion, the 114 lobe separation is a turd, in the boat and on the dyno. Just an opinion.

RichardCranium

If you change the cam, you must recalibrate the computer. These are speed/density systems. Any time you change the induction/cam/exhaust...the computer doesn't know what you have done. You may "correct" one area and make another "bad". Your computer has been calibrated for ONE particular circumstance, consult the programmer.

-Dick

Boatally Insane

iTrader: (1)

I've been talking to Mark at precision, who is programming the computer for this engine, and will DEFINATELY talk with him about any changes being made as I am building it. He has the final say as to what is going into the engine because I'm going to be running a program he has already written for a similar combination instead of mapping it on a dyno.


Doug

Boatally Insane

iTrader: (1)

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