WOT RPMs for my OMC?

[Watercanuck]

Hey all,<br /><br />I have a 3.8L OMC in a 20' Tempest Cuddy. WOT is 4000RPMs. Is that correct? If not, what should the RPMs be at WOT on my boat?<br /><br />Here is a pic of the boat:<br /><br />

<br /><br />I'm only getting about 30MPH on top speed. There was water in the fuel, emptied it out of the fuel filter but now the carbs needs to be cleaned out (will make another post about that).<br /><br />Any information/advice would be great!<br /><br />John

 

[pvisser]

Re: WOT RPMs for my OMC?

I have almost the exact same boat, and same engine. I get 4500 at about 35 - 37 MPH.<br /><br />Engine RPM and speed are usually determined by the prop. Change your prop pitch, and you will get better take off and less top end, or less take off and more MPH.<br /><br />I find a 14 Pitch is the best fit for mine.. But there are alot of guys out here with more prop knowhow than I have.<br /><br />BTW: Most reputable marina's or boat shops will "Borrow" you a prop with the "you break it you own it" attitude. I "borrowed" 3 props from my retailer, and ended up keeping a 14 and a 13. 13 has more out of the hole punch! But I generally use the 14.

 

[Watercanuck]

Re: WOT RPMs for my OMC?

Thanks Paul,<br /><br />I'll give this a shot and see if that changes anything. I'll do it after the tune-up.<br /><br />John