tropez

I have two 454, 330hp lh&rh rotation looking to replace both and would like to upgrade not sure who I can order from. I am currently running mk-iv and they are still running ok one is recent rebuild and other is aged. I dont have any room for w-or h- but I need about 100 horse more I have a budget (dont we all) about 9800.00 guys help me out I live in a desert and no major marine distributors

BY U BOY

Why noy just rebuild?? Bore em and stroke em some good flowing aluminum heads and you will easily have over 100HP more than they are now. Do a search for 454 on roids.

Good luck.

tropez

I would but not happy with engine rebuilders local I have one complete motor sitting in my shop that was a bad rebuild
last year
I have a feeling that a long block or complete would save time and money at this point

BY U BOY

There are several reputable builders on this board that can help you out. Give them a call. You can always ship the motors out to one of those guys.
Precision marine in New Orleans
Gellner engineering
JC performance
Ateco
Ect.

tropez

I will google and call? Am I asking to much from the motors and keeping reliability?

BY U BOY

No there are a bunch of guys running mark IV 454's with good HP and reliability,Myself includedNow if i can get this damn carb tostop acting up on me

HaxbySpeed

You can order Gm performance parts# 12568774 454HO. There are only a couple things you will have to change to make it ready for you boat. It comes with a forged rotating assembly and 8.75:1 compression so you can run cheap gas. It makes 425 hp and 500ftlbs. I have used dozens of these motors and can give you the formula for 440hp and 520ftlbs right out of the box. Try Scoggin Dickey or Pace performance..
Good luck.

KAAMA

iTrader: (1)

Just trying to figure out want you want......you are looking to upgrade the 330's you have now??---OR...you want to totally replace them with 2 new engines?

If you're running a better breathing aftermarket exhaust system, then getting an additional 100HP from a Merc 330 engine shouldn't be hard to do on a $10,000 budget. If you can swing the cash....a good aftermarket exhaust system is going to help your engine make power everywhere, but without it you should still be able to make 380-400hp which sounds like your goal. You can always add an aftermarket exhaust system later and it will should give your engines a pretty good kick...especially in the midrange.

EXHAUST....is your exhaust system currently an aftermarket exhaust system or is it a stock Merc system???

HEADS...Depending on the condition of the heads you can retain the stock GM heads you have now and save big money---just have them checked and inspected. (I assume they are the "peanut port" oval port heads). Just do some simple pocket/bowl porting to them while paying special attention to the short radius's. You can retain the same stock valves size, but just replace them with some good aftermarket stainless steel valves.

VALVE TRAIN....will need a cam upgrade, new lifters, retainers, locks, valve springs to match the cam. Replace the stock stamped steel rocker arms with some good quality brand rocker arms. I would also swap out to a larger 3/8" push rods and push rod guide plates.

BLOCKS...It would probably be good to have the block bored .030" and have the cylinder bores "bore notched"....usually good for another 20-30 addtional HP. "Bore notching" must be done who understands the concept and knows what the hey they're doing! Also, have the block "square decked", "align hone" the mains, and finish hone the cylinders with "torque plates".

PISTONS...Replace the stock cast pistions with some new forged pistons.

CRANKS....You can retain the stock cast cranks...just have it checked. Even if the crank must be turned .010" should be fine.

RODS....Have the rods shot peened, reconditioned and add some good ARP aftermarket rod bolts.

INDUCTION...Have the stock cast iron intake manifolds replaced with some aluminum Edlebrock "Air-Gap" intake manifolds and replace the Rochester carbs with some Holley 750 carbs with mechanical secondaries.


"RMBuilder"/Bob Madara of Marine Kinetics (N.Y.) can help you with a specific cam design that will be tailored for your particular engine application and set-up. He has helped a lot of people here and would be an excellent person to consult---very reasonable too! Bob's number is (585) 654-8583

Have fun!

dogturd21

This is the exact motor I got for my Velocity- from Marine Engines Inc. The difference is freeze plugs, marine intake with bronze inserts and a few other minor differences. I think it can be had for less than $5000 each. Additionally I put EMI exhaust on it and a few other minor tweaks. 200 hours later it still runs really strong.

HaxbySpeed

The most important is changing the oil bypass valve in the filter pad from the 11# to a 30# for remote oil filter and cooler. Not difficult at all..