86 250ccp advice please

[jetfiremuck]

 I have a 250 ccp  hull and have just installed a Johnson 91 250v8. Any idea of the prop size needed ?  Thanks

[mshugg]

The mercury prop selection tool will get you in the ball park. https://www.mercurymarine.com/en/us/propellers/selector/#!/step-one

They may not have your exact engine. But you can plug in your performance goals and get close.  It was spot on for my Merc 150 on a 200 CCP

[GoneFission]

An OMC 250 V8?  Wow - don't see many of those any more!  She should get up and go with that on her - because the 250 is actually a detuned 275, and your can build it up to 400 without a lot of work.  The OMC V-8 was nicely balanced and runs smooth, but the gearbox is not as robust as it could be, so don't hit anything...    Regarding props, 19 or 21 pitch stainless would be a good start, but I'm guessing 23 pitch might be better.  I think I've got a 21 around the shop somewhere, but it probably has a Merc hub.  Those OMC V-8s were powerful, but thirsty and heavy at 550 lbs.  If you get a chance - take the airbox off and run it without the cowl for a few minute - the sound they make is LOUD, but amazing...    Post some numbers when you get it running right - should be interesting!