Performance upgrades for a 7.4 mercruiser?
 

I just picked up a 1995 thoroughbred velocity 22' with a stock 7.4, not a magnum. What performance upgrades do you guys recommend? Was thinking of carburetor, intake, cam, manifolds. Any ideas of companies or part #'s if anyone has done a similiar project. Thanks!!

Not to sound like an azz... search, there are at least 100 threads on that subject.

Readers digest version;You can reuse the block. Cast crank and little rods are weak points so forged crank and better rods. Next the peanut port heads... replace those, Then on to the carb intake cam and manifolds.

There are ways to do it without completely breaking the bank using take out parts etc.... search and ye shall be rewarded

find out what motor you have first. If its a Merc Mag you have a good starting point, as Rob said the smaller 330 internals are a bit of a weak point. You can pull 450 hp or so and still be safe but not much more. If I was going to try and squeeze a few ponies without breaking the bank its a simple recipe, I would toss on a knock off air-gap ebay intake a decent cam and find a deal on some GIL exhaust. Exhaust is probably the biggest hold up on stock engines and without changing that most mods will be minimized.

Run the 330 till it dies and save your money for a 502. My engine is a 330 bottom end with 188 heads, Isky 270/280 mega cam, scorpion roller rockers, edelbrock intake and carb. Engine only made 407hp. Lot of work for a few HP. Cam is not that big because when I built the engine I did not have my Gil exhaust. Below is the dyno sheet.


[ATTACH=CONFIG]529538[/ATTACH]

It's a 22 Velocity. It will respond to any small hp upgrade. Those boats move out with little hp.

So, it depends on what $$$ to make x hp vs $$$ for a different motor.

Good point. And if he does new exhaust at the same time he can run a bigger cam then what I got and get the HP up more.

Great info guys!! Thanks. That gives me a starting point.

I have a 2 bolt 454 from an rv. Stock crank, Scat I beams, Comp XM284HR Roller cam, rectangle ports, single plane intake and a Quick Fuel 750 and it pushes my 26' Seebold with a 24 pitch 4 blade to 70 at around 5100 rpm. I wouldnt want to spin it any higher than that with a stock crank. Whoever says 2 bolt blocks are junk are wrong. As long as its an N/A build they hold up fine. Your boat would boogie on down with a mild 454 build. My buddy has an 89 23' Regal Velocity with a 365 horse 454 mag with Stainless marine manifolds and he gets 73 with a 23 pitch Mirage. Those little boats are really quick! Good luck!