Re: [OMC-Boats] She let me down...

Question about the choke setting as per the sheet that comes with the
rebuild kit. It says to open the throttle to wide open then measure
the gap between the choke butterfly and the throat. It's lists the
measurement as I think 1/8". But my gap is much larger than that and
was before disassembly. Should I bend the tab and set it per their
instructions, or is this maybe a setting for a different motor? It
doesn't seem right to have to move it that far from the factory
position.

Also, on the choke cover, it's indexed and adjustable. Previous owner
had it set 2 notches from the richest setting. But the middle looks
like the default setting. Should I put it back to default now that the
carb is freshly rebuilt?

BC, thanks for the info. I'll hook up the vacuum gage when I'm done.

On Fri, Sep 18, 2009 at 12:08 PM, BC Howk <bchowk@...> wrote:
> Justin,
>
> I've been saying this on the list a bunch lately, here is a link with some
> detail on the tune up procedure I use...
>
> http://www.allpar.com/fix/carb-tuning.html
>
> I like the vacuum guage procedure because you can tune your engine "BY THE
> NUMBERS" no room for subjectivity...
>
> the link will back me up on this, get it running and warm, check your
> timing, get the idle speed (on the port side) in the ball park, adjust your
> port mixture screw in till it stumbles then out untill you peak the vacuum.
> adjust your starboard mixture screw in till it stumbles then out to peak
> vacuum...repeat...timing, idle speed, mixture (peak vacuum) untill you can
> get no further improvement.....BY THE NUMBERS you are looking for timing 5
> degrees BTC (at idle), idle =550 RPM, maximum vacuum possible with the
> timing and RPM dead on (vacuum reading will vary by engine but guessing you
> should be in the 20 PSI territory)
>
> The only difference you may have from this car tune up proceedure is that I
> don't believe you have a vacuum advance on your distributor (a little cone
> with a vacuum hose that goes to a vacuum port on the carb)...So you will be
> able to ignore the golf tee part,
>
> SIDE NOTE: When you get your manual it will talk about the mechanical
> advance but basically the advance curve is controlled by weights and springs
> inside the distributor and are pretty light compared to "normal" automotive
> applications. Boaters aren't starting and stopping or changing gears so if
> you throw the throttle down we want to get the timing advance in pretty
> quickly to get us up to max power to tow that skier and once we get up to
> speed we stay there for a while...
>
> hope this is helpful.
>
> Cheers,
> B.C.
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Received on Friday, 18 September 2009