i know prop questions get old.........................but

[RIDEPATE]

hers' my set-up; 72 merc 650 on a 14'8 arrow glass scorpion closed bow ski boat, i'm getting 29mph@3900 rpm,i dont know what prop it has on it cause its not marked,surelly i can get more rpm's/speed than this,so what would be a good starting point for a prop??what would be the upper rpm range for this motor??or should i be looking at somehting else ??fuel supply??ect. the motor runs really good so i'm kinda torn.cont....

 

[RIDEPATE]

Re: i know prop questions get old.........................but

i know its not a race motor but i've seen similar rigs getting 40 to 50 mph,i dont think it's a fuel supply problem, i've got new tanks a hoses and cleaned the strainer,new plugs freash fuel ect. thanks jim

 

[JB]

Re: i know prop questions get old.........................but

You may be overpropped. Pull the prop and find the numbers stamped on the front hub. The last number should be somewhere from 15 to 23. Let's say yours is a 21. Go borrow a 17 and try it out. Whatever you have, go down 4".<br /><br />If everything else is working properly, you should be able to get 5500rpm at WOT. If you don't, try again.<br /><br />If you aren't able to get big changes in WOT rpm by changing props, you may have an engine problem that is limiting rpm. Go back to your original prop and fix the engine, then start over.<br /><br />Red sky at night. . . . <br />JB

 

[RIDEPATE]

Re: i know prop questions get old.........................but

J.B THANKS, i call myself looking for the prop-size,but have always found it on the outboard side (aft) of the hub, didnt know it could be found on the front side of the hub,but honestly i've never looked there.thanks jim

 

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Re: i know prop questions get old.........................but

Take your prop to a prop rebuilding shop. They have gauges that can tell what pitch your prop has.