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4 barrel carb - fuel hog

M

mharvey

Member
On a 4.3L V6 Merc inboard/Alpha 1 drive '96 model, I am trying to reduce fuel usage. I know I should just accept a big fuel bill but anyway, does anyone think it worthwhile trying to prevent the secondary barrels from opening on the carb?

I try and stay out of the throttle unless pulling a tube or skier, and dont run at top speed. I cannot recall the prop, but it was fitted for pulling a skier up and I could step up in pitch because it will run the rpm too high at top end, but if I dont go there anyway I did not think a small change in the prop would be much improvement.

The carb has 9600S and 4 more numbers on the housing, sorry I am going from memory. I feel sure the carb is completely stock in terms of jets, ect.

Thanks for any feedback.
 
Boats....Gallons per hour

Auto's ...Miles per gallon

What size, type boat?

If it is a 19-21 ft then a more powerful engine typically would result in better economy due to less power needed to move the boat. Not allways but in many cases.

You could always change the intake and carb to a 2bbl. they came that way also......
 
Usually the term "I am trying to reduce fuel usage" and "boat" are not used in the same sentence!
A boat is after all just a hole in the water that you pour money and gas into.

Having said that, a few years ago I replaced a 4.3 in a 20 ft Mirage with a 6.2 MPI bobtail package.
If you look down the post list a ways you will see my full report on the swap, but basically I think I am getting as least as good cruise fuel consumption, maybe better. But I do not have any actual before and after numbers to back that up.
Boats work hard all the time they are moving, so the fuel burn is pretty bad.

Just as an example, try putting your car in neutral on level ground at 40 mph, and see how far you coast.
Now try the same thing in a boat. You would be lucky to coast 100 ft.

Not to argue with kghost; but I don't think you would be happy with a 2 bbl on the 4.3. Performance would suck, especially if you were trying to pull a skier or a tuber. I suspect you would be putting the 4 bbl back on pretty quick.

Just my opinion,
Rod
 
Has anyone tried a fuel injection throttle body conversion kits? If I have the name correct, it bolts on in place of the carb and has all the other stuff to go with it. I do not know if it is recommended for marine purposes.

Am I also hearing wiring shut the secondary shutters wont do anything? I thought that was a cheap quick attempt at a fix.
 
Am I also hearing wiring shut the secondary shutters wont do anything? I thought that was a cheap quick attempt at a fix.
Click to expand...

Ayuh,... That'll surely limit yer Horsepower...

Seein's Horsepower comes from Btu's,...
Ya might save fuel, or just go slower...
 
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