more speed

ringmaster

Petty Officer 2nd Class
Joined
Aug 23, 2007
Messages
125
my cousin angot his boat done its a 79 sea ray 26ft with the 260 thunderbolt4 and a alpha 1 drive. we put this all in the boat. everything works fine except it tops out a 4000 rpm's and 30 mph. i know it may not me exact. it planes out but not all the way its like its not getting over the finel hump to fully plain. it has a 19 pitch prop on it im not sure of the gear ratio ill look tomorrow. the engine and outdrive are matching and came out of a 19ft boat. could the gear ratio be wrong for this boat or is the prop to much pitch. i know its not timing or fuel all that is new even plugs cap and rotor.
 

cooter2506

Senior Chief Petty Officer
Joined
Apr 8, 2007
Messages
733
Re: more speed

Go to the adult only sticky at top of page and read the post for Problems acheiving WOT. Go thru them ALL>Dont skip any I did and it bit me in the bum. LOL
 

searay3

Senior Chief Petty Officer
Joined
Apr 7, 2005
Messages
655
Re: more speed

you probably won't see much more speed, but you need to get the wot rpm's up. try a 17 pitch. not real sure about diameter, prop forum may be the place for this. If the boats new to you, do the full tuneup before spending money on props, could be it just has been neglected.
 

ringmaster

Petty Officer 2nd Class
Joined
Aug 23, 2007
Messages
125
Re: more speed

we did a full coplete tune up. its just not getting wot. i did a search on prop selection and everything said 17 pitch. we are still tweaking things the motor only has 69 hrs on it and was very well maintained.
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,319
Re: more speed

a 26er is a big boat for a single 350. If your sure everything is in tune double check your WOT with a known good shop tach. If all your hitting is 4K then it's time to start playing props.
You may also have a heavy boat too (water logged). Its 29 years old and its a sea ray.
 

ringmaster

Petty Officer 2nd Class
Joined
Aug 23, 2007
Messages
125
Re: more speed

we did a quick look at the throttel and found out when the lever is all the way forward you can push on the trottle at the carb it movesabout another 1" to 1 1/2" so it looks like its in the throttle cable cause there is alot of play at the lever on the dash.
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,319
Re: more speed

That would limit your rpms... when the hammer is down the throttle plates should be at 90 degrees to the venturi (carb hole)
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,319
Re: more speed

that's probably your problem then. Adust the cable so the throttle plate opens up completely. If you can't get the cable to adjust properly then it's stretched and you need a new one.
EDIT~
It may also be in the slop in your control box, in which case you'd need to replace that, or a combination of the both.
Try adjusting it first and see how you make out.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: more speed

FWIW, you are fully on plane at 30 MPH, probably at 22 MPH or even slower. GPS?
 

MikDee

Banned
Joined
Jun 6, 2007
Messages
4,745
Re: more speed

For what it's worth, I had a 79' SeaRay 24' Cuddy cabin with a 350/260hp Mercruiser, it was a lot lighter then your 26 footer, and the maximum prop I could run was a 17". With a slick bottom, light load, and thru-hull exhaust, the best I could do was 40mph at 4600rpm fully trimmed out. So I'd say you're in the ballpark, you might try a 17" pitch prop, but you may need a 15" prop to get the Max recommended 4500rpm WOT. You should pck up some speed as well by taking this load off the engine, but I wouldn't expect more then about 35mph.
 

MikDee

Banned
Joined
Jun 6, 2007
Messages
4,745
Re: more speed

Mikdee..... haven't seen you around in a while.
Hey Jason, I think you're the only one who noticed ;) I do hope your health, & life is getting better. I've had serious issues with arthritic knees, so I'm trying to stay away from sitting at the computer too long, and get more active hoping it will help. I have a ton of stuff to do to organize my house, & life anyway with spring coming,,, now it is just harder, & takes longer.
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,319
Re: more speed

Thanks Mike!
Winter was tough on my knees too. But I ski'd over 100 days this season so I guess I should expect that huh?? :)
And oh yeah... I'm just getting over an E Coli infection.... Fun stuff. I haven't even had the flu in years and I get friggen E Coli. Good luck with your knees bud... and I look foward to our debates :) in the forums.
Take it easy
JJ
 
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