1993 Nautique Speed question

[JasonS]

I bought my first nautique last summer and am loving it. I have a concern about the top speed and RPM's. It has the lower horsepower 351 in it and it top speed is only 35.5 MPH. The RPM's are around 3600. Is that right? If it is not what do I need to do to fix it? If it is right what do I need to do to increase my speed since I am 250 lbs. and like to barefoot, I need a little more speed.

Thanks ahead of time

Jason Skelton

[mdvalant]

you should be in the 4400-4600 range. Do you know what prop you have on it?

[Full-Force]

I think I have the lower output 351 in mine as well but my boat will do 46 - 47 mph gps verified. Not sure what prop I have but its a 4 blade prop, a 1.23:1 transmission and the boat is a SN 176.

[jdmoore59]

Your secondary throttle plates may not be opening. Are you any good with carbs?

[TRBenj]

No, that performance is not typical- you have an issue you need to correct. I would recommend surfing over to Correctcraftfan.com for some better advice.

[JasonS]

you should be in the 4400-4600 range. Do you know what prop you have on it?

No I do not but will look.

[JasonS]

Your secondary throttle plates may not be opening. Are you any good with carbs?

Good enough to have someone else look at it!!!!

[AirTool]

I would recommend surfing over to Correctcraftfan.com for some better advice.

What !?

[Mikeski]

check the initial timing and distributor advance mechanism to make sure it's working. Even with primaries only a 176 with a 351 should probably reach at least 40 MPH?

[TRBenj]

What !?

Did I stutter?

[jdmoore59]

I guess we should all follow the thread on another site.

http://www.correctcraftfan.com/forum...e-speed-issues

[AirTool]

I guess we should all follow the thread on another site.

http://www.correctcraftfan.com/forum...e-speed-issues

Blasphemy ! I am loyal to this site !!!

[JasonS]

I guess we should all follow the thread on another site.

http://www.correctcraftfan.com/forum...e-speed-issues

.

I asked the question on both sites to get information about a problem I dont know how to fix. I dont care who answers my questions, I just need some answers because I dont know anything about what is wrong.

Since I posted other info on the other site, I will post it here also.

I have since done some checking and the secondary plates DO open up if I force them open manually(that is without the engine running). It was suggested on another site to water test it, by that I mean have a driver run the throttle up and manually open the secondaries to see if the speed or RPM's increase. If it does, it was suggested that it may be the diaphragm needs replacing.

Any other suggestions now that you have more info.

[shag]

So wait, you've had it to 46-47 GPS? or it is going that fast now on GPS and just not on the gauge... Sorry if I got confused. It does sound like what the previous posters are saying though. The vacuum secondaries are not opening, something happened with the timing advance, or someone switched props on you (just kidding). Most likely fuel related IMO.
Good luck on either site! lol

[JasonS]

So wait, you've had it to 46-47 GPS? or it is going that fast now on GPS and just not on the gauge... Sorry if I got confused. It does sound like what the previous posters are saying though. The vacuum secondaries are not opening, something happened with the timing advance, or someone switched props on you (just kidding). Most likely fuel related IMO.
Good luck on either site! lol

Mine will only run 35.5 MPH at around 3600-3800 RPM.