Vibration Issue

[97_Manta_Ray_CR]

Hello to all that will help me

First off thank you for taking the time to read and give advice

I recently had my mercruiser 3.0 replaced with a newer 3.0 motor cause I spun a bearing in the other one, the newer motor is a 99 mercruiser 3.0 factory adjusted timing and carb (nothing has been adjusted since from the factory) installed in my boat and idel is great about 1000 RPMS and full throttle is fine 4400 RPMs with a 14.5x19 prop....

The issue I am having is at about 1100 to 1200 RPMs the motor vibrates alot and anything passed 1100 to 1200 RPMs or lower the motor runs smooth,,,

Now when I say vibrates I am meaning the engine and the whole boat...

I have adjusted the choke idler,,,

I would prefer not to adjust the carb since it is Factory set

Please help

Thank you again for your help
Chris

 

[Watermann]

That vibration might be a ghost you could chase for a very long time. I'm thinking you could check the ignition system, timing, plugs, wires, cap and rotor.

 

[thumpar]

The first thing is your idle is too high. It should be around 650 RPM. As for the vibration, was the alignment checked? Did the u-joints and gimbal bearing get checked and greased?

 

[Rick Stephens]

Is it possible to factory set something? I only ask since I have never personally tried a carb or a complete engine that was factory set. It isn't that hard to set idle mixture screws on a carb or to check and set timing perfectly. Being factory set doesn't mean it is perfect, even factory techs get sloppy and variances in engines make for variances in settings. Might as well not have adjustments.

 

[biggjimm]

Like thumpar, I too would look at the alignment & U-joints & gimbal bearing.

Like waterman said about chasing a ghost. Could be any number of things. Messed up harmonic balancer or the wrong flywheel or lost a weight off the flywheel (if they are balanced with weights on that engine) Just a few separate "vibration" causing problems I've personally had in the past. The list can go on & on.

 

[Bondo]

Hello to all that will help me

First off thank you for taking the time to read and give advice

I recently had my mercruiser 3.0 replaced with a newer 3.0 motor cause I spun a bearing in the other one, the newer motor is a 99 mercruiser 3.0 factory adjusted timing and carb (nothing has been adjusted since from the factory) installed in my boat and idel is great about 1000 RPMS and full throttle is fine 4400 RPMs with a 14.5x19 prop....

The issue I am having is at about 1100 to 1200 RPMs the motor vibrates alot and anything passed 1100 to 1200 RPMs or lower the motor runs smooth,,,

Now when I say vibrates I am meaning the engine and the whole boat...

I have adjusted the choke idler,,,

I would prefer not to adjust the carb since it is Factory set

Please help

Thank you again for your help
Chris

Ayuh,.... The factory set points are only beginnin' points, Not final adjustments,.....