V/P Outdrive

[Dean]

Hi,

Can anyone help? When I push the gear lever forward there's an almighty bang and the boat takes off like a scalded cat. It's as if you hit the transom with a hammer.

Is this normal or can I adjust the gear linkage or something to take the harshness out of putting it in gear.

Grateful for any advice.

Dean


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[tr7v8]

A few more clues would be useful (or a profile) is it petrol or diesel, what tickover speed is it running at. They do thump a bit but if the tickover set at a sensible speed then all should be well. Has anything been done recently?

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Draco 2500

 

[Dean]

Hi,

Its a petrol engine 4.3L GM, I think the tickover is about 1000rmp.

When i put it in gear obviuosly the revs drop and it starts to move, I think they come down to 750 rpm.

This according to the datalog equates to about 4mph, I believe that I need to
re-prop to get the speed down (on the broads), but this isn't an option at the minute due to funds.

Dean

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[Dean]

Any offers?

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[David2452]

Tick over way too high, should be about 600 no load. Just hope there's no damage if it's been dropped int drive at 1k on a regular basis.

David

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[Dean]

Thanks

I'm going to drop the tickover as low as possible.

Will this lessen the thump when put in gear?

Dean

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[BarryH]

In reality that tickover is too low. It'll stall when it gets put into gear. The lowest I would go on the V6 GM lump would be no lower than 750-800 rpm. Dropping it in at 1000 rpm shouldn't do much harm. The volvo drives use cone clutches. If it was a merc alpha, they use dogs, then it might be an issue

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[Dean]

Is it trial and error?

The manual states 750 RPM. I'll play about with it (so to speak)

Dean

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[BarryH]

umm, well sort of. Running it a 600 rpm at idle, it will definatly stall when put in gear. Make sure the fuel mixture is spot on. If it using the Rochester carb, they're a bit prone to running out of tune. Start at the low end of the rpm at around 750 ish and see where it will go into gear without stalling. Get the thing upto normal working temp first though.

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[Dean]

Thanks all.

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