JaayTeee

If all you're concerned with is how it sounds at idle , look for the old flat tappet cam used in the
HP465

hogie roll

I like this guy, he's funny.

KAAMA

Doing anything with the induction side of the engine...i.e. "huge heads", single plane intakes, and 850cfm carbs will all be done in vain without first modifying your bottom ends on those Merc 330's with cast cranks, rods, and pistons. You will need to concentrate on upgrading the bottom ends first, before you do anything with the top ends or adding any induction parts to the engines. Has your engine builder informed you of any of this yet?.

phragle

Who is your engine builder???

Fenderjack

Those 330 bottom ends work,if there in good shape and you don't run the H out of them.Got a pair in my 40 CC sport fish and I got 1000 hours on them.That is really straining them NP Cruise all day long at 34_3500 rpm.Just don't over rev them or go beyond 4800.I got a pair with 600 hrs in my 32 fountain and run them a little hard but can run all day at 3200 with a cruise at 48 mph and very dependable every know and then twist them I do agree that with all that money in the top end it would be nice to have a good crank and rods.But every one can't dump a ton in a motor and have money left to go out on the weekends.Let's face it most guys do more cruising than all out balls to the wall.I got 35 k in a pair of N/A motors but most of the time they are 3500 rpm or lower.But sound good LOL us poor guys got machine shop no engine builders LOL Just my 2 cents

Quick2500

And with small port heads, short duration cam, dual plane intake, etc, it's a decent and reliable package. its easy to put way too much head and cam on a 454, especially if you are not spinning it fast. The cast pieces in the 330 work for low power and low speed. The OP needs to decide on how much power he wants to make and where, then build the combo around that. As far as a desired sound at idle... I build for numbers, not for sound. But then again, a good combo always has a good sound.

Uncle Dave

Its got to idle sub 1000RPM-and be stable enough to idle in gear without dying - or you'll crunch the drives.

Its probably GOT to run on pump gas (92)

Those are your base "gotta haves" for any usable boat with an I/O drive system.

Even with bottom end work it needs to be "all in" by 6K as thats as fast as your boat parts in an I/O "want to spin" regardless of your mill.

Without rotating assembly work you have to be "all in" sub 5K which means a dual plane manifold will work better.

Sounds like you are doing an auto engine type thinking for a boat potentially to leading to misery.

"Huge heads" typically dont pull through the low and mid range and usually only work with higher compression at the upper 3rd. (higher than pump gas)
and the ability to skip andy kind of reasonable idle which you can't with a boat and still shift.

Small to Medium heads, (bb1) with a reasonable roller profile with the centers shortened up to prevent reversion work best with boats- at least outdrive equipped boats.

Then as SB said whose exhaust- etc...this is a big deal. (went back and saw lightning- good header)

oil cooling now you are making power etc..

Going to watch this one close.

Good luck!



UD

Fenderjack

If anything I would put a oval port intake back on with the cam change,They give you added torque on square port heads

Uncle Dave

agreed.

a bb1 might even be too much head.

UD

TooLateVTEC

How has this made it 2 pages and not one person has said talk to Bob @ marine kinetics?

Yall are slippin

http://www.marinekineticsonline.com/contact.html