fastscarab22

iTrader: (1)

stock 454 ( 330 hp ) , that is what i was told , if i iam wrong i am sorry . I was just trying to help a guy out

Knot 4 Me

4,600 max RPM for stock 330 HP 7.4's with the rev limiter set at 4,750.

Rookie

iTrader: (4)

Was it a 330 with peanut port heads?

endeavour32

iTrader: (4)

Do as others have said, get all the specs on this engine, with that info we can help you out. There was a 25 Senza on my lake when they were new with a 454 mag and yes they are a fast boat. One thing lots of guys have found out is car guys usually do not build great boat engines. What works in a car typically doesn't work in a boat, especially a larger single engine boat like yours. In order to get 515 real hp out of a marine 454 would need good aftermarket heads or heavily worked iron heads. IMO a good 454 with stock heads could make around 460 hp, if done right with aftermarket exhaust. If you're using stock exhaust drop that number to 400 hp. Even at that number you should be at 70 mph in that boat.

endeavour32

iTrader: (4)

I went and ran some prop slip numbers and guessing the slip on that hull would be around 12-13%. With a 502 and 70 mph at 5000 rpms you would be spinning a 25 pitch mirage or a 23 bravo. The fact that you are only able to spin at 4400 rpms tells me that your engine was build wrong for a boat and is not making anywhere near 515 hp. That boat with a 330 454 would run low 60's.

fastscarab22

iTrader: (1)

There is a guy on the swap shop that has a hp 500 dist and thunderbolt 4 ing for sale , $150 .00 buy it and try it

endeavour32

iTrader: (4)

I would first get us all the engine specs. I feel replacing the distributor at this point would just be throwing good money after bad. One question for you, is the bottom painted?

Achmed666

Sounds like your running that boat with an engine similar to that of a Fred sanfords truck, it just does knot have any power. Maybe you are running it on 6 cylinders.

project tt

haha, you guys are great. The boat has an edelbrock 750. I was told by the shop that I am starving the motor of fuel. Secondly, it has a Corsa thru hull exhaust. The heads are the huge rectangular port heads with roller cam, roller lifters, and roller rockers. Bored 40 over with forged sem-flat top pistons. The valves are upgraded to as big as they fit. THe ignition is a stock prestolite i believe. I dont think it i am running on 6 cylinders haha. I should have more rpms thats for sure. Maybe throttle doesnt open all the way idk. I thought it was when i put motor in.

endeavour32

iTrader: (4)

We need more info! What cam grind, intake, compression ratio. Biggest valves doesn't mean anything- what are the actual sizes. Yes the 750 is a bit small but your not going to lose 20 mph from being 50 cfm to small. There are bigger issues than the carb size. Also Corsa through-hull doesn't mean much either, what are the actual exhaust manifolds? If you don't know, chances are they are just the stock restrictive manifolds.