If you don't mind paying the fines issued by the Coast Guard, use a street carb.

Seriously though, go with a marine type.
The bowl vents and throttle shafts are made so fuel cannot leak out. There may be some minor changes in the air bleeds and fuel circuits but otherwise there's no real difference.

 

buy the marine carb - if you have a problem and your boat catches on fire not only will you be fined by the Coast Guard but your insurance company will not honor the claim after an inspection and THEY WILL inspect the carb.

Marine Carb. Only way to go...

plus: You may get inspected by the Coast Guard anyway: it's rare but it does happen.

 

Cough cough BLOWER cough cough
You need a BLOWER

 

Cough cough,I have a Marine Quadrajet and manifold,,,for half of what you would pay for just a marine carb alone !
cough cough :laugher:

 

he has a edelbrock AFB on there now, Rochester wont fit without an adapter plate and that is sort of moving in a backwards direction if you ask me

 

That's why this comes with a manifold too !!

And depending on what size he has now,I'm not so sure it's a step backwards....I'm not sure what he's running,but a carb alone will not give him much gain.

But I was just funnin anyway because of Jayl13's post.

 

sorry boatnut
i've already decided on the Holley 750
was more or less just curious of differnces between
h2o and land carbs
i think i'm just going to go with the marine carb
NO BLOWER jay...maybe

 

Deez Pleez,,,what motor are you running and what carb is on there now ??

 

its a 454 w/some mild work done to it
mild cam, performer rpm manifold,
i changed the heads to large oval, they were originally
peanut heads
i don't know cam specs cuz the previous owner installed that
the motor was just redone the end of last summer
only has 5 hrs on it
however i think the carb on there is only a 600 because
it won't rev over 4200 and seems to run a little lean

 

Sorry,a couple of more questions...What size boat is it in,what size prop are you running,and do you happen to know the year(boat)motor ??

Sorry for all the questions,just don't want you spend your money and not get any gain !

 

25ft 5in doofus i bought it from has a 19p on there
as of right now i haven't put a new prop on
that is the other thing i have to get this year
planning on a 25p Mirage
the motor WAS a stock 330
right now it is probably around 360-370HP

 

Why the 25P ?? If you can't spin a 19 you will not be able to spin the 25 .You would be dropping aprox. 500 RPM's than your spinning now.

Man I just don't want you to throw away your hard earned money...
Julie from Throttle Up can help you with prop choices. I was running 415 HP in a 25' and only turning a 23P..

I also don't think(unless there is a problem with it)that a carb is going to satisfy your needs.
Are you running stock exhaust?

 

well there is some problem since he cant wind his engine up above 4200 RPM's with a 19 P on there

most of us would take a 19 and over rev our boats and blow em up from a 19
Russ, try one of my 21'st to start
wont cost you a dime (unless you trash it :snide: )
not a penny
just try it
see what it does or does not do

then if that rev's you down lower than 4200 something is majorly wrong and carb might be part of that
if engine is not getting that much fuel and is starving it wont rev high enough
honestly, I would have figured same thing, not enough carb
cause any 330 should be able to turn 23-25 P with minimal effort
I think your HP #'s are a bit high
I would put you in at 340-350 but still quite enough to spin a 23-24-25 P on a single 25' weighing around 5000-5500 Lbs
you might not get the best out of the hole performance but your cruising speed and your WOT top end (assuming you can get your RPM"s up over 4200 and start getting towards the 5000 mark would yield you some decent speeds)

Anyone else ever have an IMP eleganza 255 that they played around with props on?
and personally I have NEVER heard of a 330 having a 19 P on it from mercury
21 was MINIMUM merc put on bravo's to my knowledge

Jason

 

oh before propping it, make sure you can spin that 19 way UP there in the 4800-5100 RPM range
cause Boat Nut is right
if you cant turn the 19 over 4200 your NEVER going to get a 25 to turn
I remember you saying your having problems with prop blow out is this true?
if so that should make your RPM's exceed 4200 , if not you have another problem you need to look into
like slip the prop and do a "burnout" in the water
your rpm's will just shoot way up with no water resistance on the prop and have you bang your rev limiter (if your boat has one)
Trying to help ya bro


BLOWER
BLOWER
BLOWER
BLOWER
BLOWER
BLOWER
then 27P
BLOWER
BLOWER

 

any ideas than
before the motor was done i could run 5200rpm
all day
why not now with a little more hp
i am experiencing major prop slippage
the boat takes longer to get on plane and higher rpms than before the rebuild
i figured this was due to an increase in power and not enough "traction" so to speak

 

if the carb is restricting the airflow to the point where the motor won't turn over 4200rpm's than the blowout would never bang the rev limiter anyways...right?

 

it is due to increase in TORQUE not HP
HP is an imaginary figure Torque is an actual measurement
your able to turn prop with more FORCE than before which means you can up your pitch in prop BUT you need to be able to turn it with more force with increased RPM's
if you dont have the RPM's then your not going to get speed but you could tow a 46 rough rider back to the docks like a tow truck

follow?
slippage is due to not enough cup in the blade which you know all that already.
more cup = more bite in the water
Labbing a prop will just about always yield a few more RPM's but that is by thinning and balancing the blades on the props themselves but in your case (and in mine) not worth the investment.
you make sure your actually able to open carb 100% open and not an adjustment with the cable, throttle golf club thing you have at the helm?
Maybe it is time to trash that thing and get a cheap set of throttles ?
somtehing to think about
your power trim working okay?
anything seem weird, any miss in the engine?
J

 

if the carb is restricting the airflow to the point where the motor won't turn over 4200rpm's than the blowout would never bang the rev limiter anyways...right?

No imagine car in park and you rev the engine
no resistance
prop blow out is just about the same thing
prop no bite in the water, sort of freewheeling back there and not grabbing water just sort of splashing it out of the way
should shoot your rpm's right up to 5000+
can you even rev it like that in the driveway?
up to 5000?
might be a timing issue or cap/rotor/plug/wire problem?
but with blow out there is no reason you should not get it above 4200
now rule of physics
more power= more fuel to make
but your engine is not really breathing THAT much better than it was prior but I dont know the exact specs of your cyl heads either and valve sizes and cam specs
I would call Joe the Douche and get the head specs and see if anything was ever done
Mabye if your heads are breathing really well but your stock exhaust is restricting you too much then it cant push out exhaust fast enough and backing up preventing you from winding up too much
(careful might blow exhaust gasket from that problem)
tough to diag on computer
j

 

last run of the season the carb developed a lean pop under load
makes sense to go to bigger carb...to me anyways
boatnut to answer your question the exhaust is stock

 

Well as you know first hand mine was popping (both of them were) and either needed to be rebuilt and new needles or sent to the scrap heap
you know what the outcome of that was as well
HOLLEY to the rescue!
hell you should have had that thing dyno'ed like I am
Dont trust that A-hole engine builder to save a worm from the dirt
J

 

well thats where i think the problem lies
the engine runs strong
i'm not worried about it
but i do think the carb is restricting the potential of the motor
when you swapped carbs you gained more RPM didn't you?

 

Well a dyno would really be the answer..
Also try to find out as many specs from your engine builder as possible...
Believe me(and I know the ladies will disagree ) but BIGGER is not always better.Everything needs to be built in relation with the components you are running..

I am not saying that you don't have a problem in the carb,like Jay said were talking over computers,but I don't believe a Carb is going to solve your problem.

Before you buy a carb,see if someone has one you can try. If we were closer I would let you try mine,but Jay also it won't fit your manifold.At least you will have a idea before spending $500.00.

 

well thats what i was going to do BN. Jay has 2 800cfm for his ride. i wanted to swipe one of them and give it a whirl before i do anything. granted his carb is a little bigger than where i was thinking i need to be however i'd know for sure if my current carb is holding me back

 

now your cookin!
Let us know what you find.
Inquiring minds want to know

 

You should find out for sure what CFM your current carb is first. As boatnut was trying to get across, you can throw tons of money at these boats with no gains to show for it.
You might have an ignition problem.
Like everyone said, if you can`t spin a 19P, you sure won`t spin a 25P.
Do a little investigating before you pull out the wallet.
Just my 2 cents.
Donnie