Did I spin a balancer?
 

I've been breaking in a new motor , 600 inch, in my 41. Kept it at 35-3800 for the whole weekend. Last night, final blast back to the ramp, took them to 4500 rpm, major vibration up on plane. Dropped off plane, neutral, no vibration. Engine revs cleanly and smoothly in neutral. Stuck it in gear, hatch up, throttled to 3000 and the engine was jumping like crazy, headers shaking big time. Neutral, no problem,smooth. I thought is was a prop blade or drive. Prop is fine, drive fluid is good,full, prop turns smoothly. The motor is on a drive line with about 2 feet of drive shaft and a carrier bearing in the rear where the drive fits in. On the hose, drive shaft spins freely, prop is smooth turning. Its only on plane or struggling to get there. 2 years ago, I shear the blanancer key on the other motor, but it couldn't be revved to 1500 befor the whole thing shook in neutral. Any ideas?

If the balancer went bad you couldnt rev it in neutral I would think. Stock balancer? or aftermarket like fluidamper or?
If stock.. the only thing that can go bad is the outer ring seperating, and if that happened it would wobble. But its takes lots of revs for that to happen. They usually last forever.
I would look at coupler, ujoint or bearing first.
Dan

its an older Fluiddamper. There was a smell of burning plastic/rubber when the vibration started .The day before, it chucked an alternator belt. I can't check it until Friday so I'm hauling a new one up to the river with me.

DanB, front ujoint toasted. Now I can send the 350. balancer back. good call

Thats 2 for 2
I think I'll keep my mouth shut from now on and quit while I'm ahead:)
U joints are cheap...glad to hear you got off easy
Dan

The're not cheap when they explode! :mad: :(

Like mine did this weekend.:(