Max RPM on a 330 merc?
 

What is the max rpm on a stock 87 330 merc. I know the sticker says about 4400, but I didnt know if it could take more.
Also it has 425 hours on it
Thanks Chris

A stock 454/330hp, 21 years old with 425 hrs.

Better stick with 4400 or maybe 4200.

you best do what whatabout1 suggested, you push that motor to hard you will be paddleing.

I think the factory rated that motor for a max of 4600 rpm

dont push it too far. from my experience with 330's they do not like to be pushed past 4800rpms and that was on a brand new motor. 21 years old i would give her a break and keep it under 4400rpm. other wise a 330hp is a great motor and will give tons of reliable fun if not rev'd up high. good luck

They sing at 5000. In '88 all the Velocitys new were propped to turn 5k. I had many customers and friends with them. Just run and burn the belts off them. If it turned 5k you cruise at 4200. I know boats that never run any slower if off idle. My friend Ronnie put 325 hours on his boat the first year in '87. He was the only one to ever have problem. He broke a crank playing in rolling 4 and 6's one stormy day in the Chesapeake after 795 hours. Most wore the boat out before braking any thing in the motor.

Those 330's were great motors. Interestingly the 30 Velositys would out run all other 28 Bajas,and 30 Scarabs with Magnums and 420's.

The good old days.

I agree, Lugging it down in the low 4's by overpropping it is probably worse for it. 4600 to 4800 Is best and faster too.

Jim,

Now I'm curious. I've got a pair of '94 454/330's in my Dominator. Roughly 500 hours on them running through 25 pitch Mirage props. Is it really safe to run them up that high? Thought the cast internals wouldn't hold up to spinning that fast??

425 hrs is nothing for a 330. Spin it up to 4600-4800. It won't make hardly anymore power past that point.

I agree, add another 1000 hours then you can worry.

Griff, I am only turning up to 4200. You think it's safe to turn 4600?

You actually put more of a load on the motor dragging it down to 4200 or 4400. You are probably in the secondaries at 3200 or 3400. At 5000 k your not in the secondaries till later maybe 3600. You can cruise at 75% throttle at 4000 or 4200 endlessly.

Having bigger motors is nice but they don't live near as long. we would burn the belts off and add gas. Pretty good boating.

I have a 454 started life as a 330. Have about 300 hours on it now.
Spins 4800 all day long in my jetboat. I changed the heads, cam, intake, and exhaust about 5 years ago. That really livened it up. Could probably handle 4900 or 5000 now but will need a shorter impeller. It's a workhorse and 4800 seems very safe (especially for non-forged internals), so I'll leave it like this til the motor wears out or lets go.

I think it's a good motor with the right cam, heads, and exhaust.
When it's rebuild time, you can pick up an easy 100hp with a few simple changes.

Enjoy!

4800 is a good number. Most 330's that fail that I've seen is a result of a leaky exhaust like a riser gaskets. I suggest you change them every few seasons don't wait for them to begin to weep. Its cheap and easy to do.

Easily. Like was said, you're actually lugging the engine some. dropping down 2" in pitch or a good prop lab job will get you there.

i would lab the props your spinning and get the rs up to 4600-4800 and you will also go faster.:D

Got a buddy running stock '96 330 bottom ends with Brodix heads, roller cams, Merlin intakes, 4150 Holley's, MSD inginition, and CMI e-tops. Runs them 5K with no problems. Probably would not want to spin them much faster for any length of time.

Prop for 4600rpm with a normal load; then you'll be at 4800 real light or 4400 real heavy.
The engine will not make more power above 4600.

Thanks for all the opinions its running about 4500-4600 rpm and just wanted to be safe.
Chris

That is exactly what I've done with mine. I tried 4 props before I found the one (Revolution 4b 21p) that put me in that sweet spot.