24 offshore

[101numlock]

my budy just aquired a 24 ft Grady Offshore with a 350 CI inboard/outboard i believe it is a 1986 model. it the has less than 500 hrs on it. My question is he is maxing out at 3800 RPM and at just over 18 knots!. motor sounds good, and i confirmed the linkage is moving the carb to wide open. What RPM and Speed should he expect out of this boat ball park? seems like it should at least run 30 to me?

 

[JeffN]

What prop is on that drive?

 

[101numlock]

not sure

there are not any numbers on it? if properly propped what RPM and speed should he get? We are trying to narrow the problem down either motor or prop or if that is about as good as this boat should get?

 

['84Offshore]

I have the same set-up.

I cruise @ 3600RPM doing 30MPH, WOT is 4600RPM.....max speed ~39MPH.

I have rebuilt the engine w/ Vortec heads, probably pushing 300+ HP, have a 1.5:1 gear ratio O/D and turning a 17" prop.

What type of outdrive is he running? Sure it's a 350 and not a 305?

 

[101numlock]

not too sure of anything right now but i will know something for sure by sunday, my father is going to check the motor out and i plan on running the block number on it if i can find it. I will take some measurements of the prop so i at least know what he has. Either way i am pretty sure his max should be well above 3800RPM and 18 knots. Thanks for all the help any other sugestions or what prop size he should be ballpark would be helpfull. How do you go about finding out the gear ration on the outdrive anyways?

 

['84Offshore]

Check out this site........ http://www.mercstuff.com/drivegearratio.htm

You should have a 1.5:1 ratio for a V8.......and if it's higher (1.65:1) thre RPM's would be higher anyway, so I doubt it's the outdrive.

WOT should be somewhere between 4400 and 4800RPM.