87 3297 runs slow is this normal?

[snavaroli]

My 3297 Mariner at 3,000 RPM only does 8-10 knots max. I can get up to 12 knots at 3500 rpm. I have seen other forums of people doing up to 17 knots and faster at 2700 rpm. It has the dual 350 engines and V-Drive. Everything sounds ok when running. Any assistance would be appreciated.

[g36]

Havw you checked the advance on the distributors?

[km1125]

Sounds like you're not getting on plane! What's the bottom of that boat look like?

When you say "350", do you mean 350 CI or 350 HP... Crusader makes both, so it gets confusing.

In your profile, it says 3697 but the title for this thread says 3297... which one is it?

If you have 350 CI and it's a 3297, you should EASILY get over 17MPH, if you have 350 HP and a 3697 same thing. I'm not sure what 350 CI in a 3697 would do, but I'm sure it would get up on plane and over 12MPH unless it was very heavily loaded.

[tomschauer]

Will both engines come up to 4000 rpm? If not you may have a dirty bottom or a prop issue. If they go to 4000 and you are on plane, back them off slowly and find out what rpm you fall off plane, probably around 3400. If this is the case, you may need to bring it up to 3600 or 3800 and then back down.
Also make sure your tabs are fully retracted (up).

[snavaroli]

This is the 3297, 350 CI 260 hp. I was able to dive the bottom of the boat and remove a couple clusters of muscles that had grown on the metal pieces. It also seems that I have to have the starboard engine throttle much further forward than the port engine for the sync needle to equal out. however the RPM'S are still within 200.

[waybomb]

Sounds like you have multi issues.

If you have muscles under water it's probably time to pull it and clean and repaint the bottom.

As for the throttle partly offset, with engines off, move the throttle full forward, then go below and see if carb is fully open. You may have loose linkage, mis adjusted linkage, or severely stretched cable.

[snavaroli]

Thank you, I am pulling the boat and pressure washing the bottom this weekend and will inspect the paint. The throttle advice sounds like a must check. Thank you I will try that.

[snavaroli]

Bottom has been cleaned and paint is in great shape. It appears at full throttle the port engine can barely get over 3000 rpm. I still need to check to see if both carb are opening fully at full throttle but Either way the boat won't get up on plane. I was shocked to find out this boat didn't have trim tabs and am wondering if that is a must do this winter.

[tomschauer]

if you cant get over 3000 rpm's tabs wont help you. You need to find the problem with the driveline.

[km1125]

Lots of easy things can be checked on the engines. If you don't know the state of the fuel filters, then change them so you know. Also check the mechanical advance on the distributors and the base timing.

Will the engine rev over 3000 with no load?