Top speed

[Choochoo]

Anyone know what the top speed should be on a 1989 Supra comp ski boat with a ford 351


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[Cooose]

my guess would be that it would depend somewhat on the prop.

try the search feature.

https://forum.supraboats.com/showthr...d-in-a-89-TS6M

[Jetlink]

Anyone know what the top speed should be on a 1989 Supra comp ski boat with a ford 351

Hull design limits you to around 44-46MPH on the water. Prop and engine speed are the other two variables. What prop are you running?

[Choochoo]

Honestly not sure I think it's the stock prop that came on it. I'll have to look this weekend and post a picture of it. I'm topping out at 35 wether there's 8 people on the boat or 1.


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[michael hunter]

That looks a little low . You must find out what prop you are running and what RPM its turning . Are you barefooting ? Why do you need more speed?

[Choochoo]

Speed factor is just cause I like to go fast and want my boat to run like it should. But the RPM stops at about 3600


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[cadunkle]

WOT RPM should be in the 4400-4800 range. Check initial timing and that advance is functioning. Initial timing should be in the 6*-10* range and full advance of 36*-38* by 3000 RPM. Set initial timing if needed and if not advancing, clean and lubricate the advance mechanism.

Verify carb secondaries are opening, appropriate fuel level in bowl, and passages are clean. Clean and adjust as necessary.

How are you checking speed? Use GPS if you are not, and calibrate your speedometer to match GPS at your usual speed.

[crystal waters]

WOT RPM should be in the 4400-4800 range. Check initial timing and that advance is functioning. Initial timing should be in the 6*-10* range and full advance of 36*-38* by 3000 RPM. Set initial timing if needed and if not advancing, clean and lubricate the advance mechanism.

Verify carb secondaries are opening, appropriate fuel level in bowl, and passages are clean. Clean and adjust as necessary.

How are you checking speed? Use GPS if you are not, and calibrate your speedometer to match GPS at your usual speed.

Had 87 comp with 351W
Now 89 combrio with 351W
Running at 1200 ft above sea level
In both cases top speed varies between 44 to 46 depending on load.
That said , seldom go there as I tend to baby my boat.

[Choochoo]

Okay thanks I do use gps to track my speed. I'm getting the carburetor rebuilt this week and gonna swap it over to electric ignition this weekend. I'll adjust the timing when I do it and let you know if anything changes


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[Choochoo]

Has anyone found a way to run an onboard out of the water without having to buy the setup online?


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