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James James is offline
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First recorded activity by BoatBanter: Jul 2006
Posts: 163
Default 4.3 2bbl to 4.3 4bbl

I believe there are multi-speed xmissions based on the powerglide two speed
gm automatic. Smaller boats don't have the room for them. They also add to
the price. I tried a land+sea variable pitch prop (got one used) but it
takes considerable "tweaking" to get to to work optimally for your boat.
Decided it wasn't worth the trouble. If you have enough engine the only
real issue is holeshot. Otherwise the operating range of the boat on plane
is well inside the power range of the engine. Usually you can prop it
slightly one way or another to give a little preference to which ever you
can the most about, holeshot or topend. I have a 21 and a 23 pitch props.
For watersports I use the 21 but it will let the rpms get over 5k so I have
to watch not to run it a wot for more than a minute or two.

"James Sweet" wrote in message
news:zYcYg.392$AR6.222@trndny02...
James wrote:
A bigger carb will not particularly improve your holeshot. Make sure it
is tuned up and running properly. One thing you can do is under prop it.
By putting a smaller pitch prop on the engine will be able to rev quicker
out of the hole. It will be up to you to not over rev it while running
at high speeds though by you backing off the throttle. I would drop at
least two, may be 4 sizes. In other words if you have a 21 get a 19 or
mayybe even a 17. By used on ebay or elsewhere and you can usually sell
without much loss. Keep you old prop and you can swap them back and
forth depending on what you are planning to do for the day.


Kind of makes me wonder why boats don't have a 2 speed gearbox, wouldn't
even have to be synchronized or capable of shifting under power, but to be
able to select speed or acceleration without swapping the prop could
really come in handy.