Prop for a 190 200hp Johnson on a 20' SF
 

Can anyone point me in the best prop for this scenerio.... I believe I have a stock aluminum prop right now and get about 5000rpms until she starts beeping the low oil warning horn. Wondering what sort of props I should look at. Think the fastest I ever went with a GPS was 43mph. I feel like there's more I should get out of it. Before I go into researching props I'm sure someone might have had this setup before and knows more than I do.

Thanks so much for any advice! The motor is also a counter rotation that I picked up from an old grady white pair....it was cheaper than the other one....was working on a budget.

Iceboy

Quick question...."low oil warning horn"??? Not the temp/overheat horn sequence of beeps?

Oh yeah, a 1990, right? Carb engine? Pitch and diameter of the prop??

Or maybe a fuel restriction alarm?

I would think it would swing a 3 blade sst 21 pitch if the motor is a strong motor but a 19 pitch of the same prop may be the ticket.

FWIW i run a 200 mariner on a 20' SF and i run a 21p laser2. I max out at about 5200rpm lightly loaded. next summer im thinking of going to a lesser pitch prop. the enertia 19p has been catching my attention or the 17p or 19p mirage plus

19P viper . . . make sure cavitation plate is about 1.5" - 2" above the bottom of your hull. too low and you lose a LOT off speed. Too high and you'll blow out around the hard turns.

Thanks guys, I'll start checking on those props! I just checked and my prop is part number 431930 and says 15x17 on it.


I'm pretty sure the horn I get is low oil horn which chirps every 2 to 3 seconds. I don't think it's the low fuel warning which is continuous. I have 3/8" fuel line and the big Sierra 18-7866 fuel filter(10 micron). It's always happened since I got the motor. I even switched the VRO once with a 1994 VRO and the same thing happens...I pretty much only run up to 4900rpms or below. And only 4900rpms when we're showin off. I go pretty easy on her since it is an older engine. If I can figure how to post pics I will. I haven't in three years since I redid her.

Thanks so much again!

Dave

Cavitation plate is either right on the transom line or slightly above, maybe no more than an inch. I just put this motor that I bought apart from the hull in the same holes that were there from the factory I guess in 1983 and everything lined up. 25" shaft.

# 1 - Since is an older Rude DECARB DECARB - maybe twice LOL -

#2 seems like it should swing a 19 but it seems to like a 17 based on your RPM - I love the Stilletto I have, such tremendous change and so trim responsive. You can find them used on ebay too for less than 200 - 150 is great. You will have to raise the motor as stated to 1.5 to 2" above when going to an SS prop, 2 at least if you go with a stiletto or mirage. Alot of guys like the Mirage although I can't compare - I couldn't find one

#3 you really need to figure out what the alarm exactly is, your on a budegt you don't need to lose it.

The best way to explode an older OMC is NOT decarb it - the carbon builds up in the ring glands - motor will even run alot better too with more compression. My fav is Seafoam - get the lawnmower can 1 or 2 gal , follow the directions - I think they say 50/50 gas and Seafoam - 1 gal of fuel is fine. Warm it up on the muffs good - pull the fuel line off and stick it in the can and fire it up - again follow directions, run 15 mins sit 15 until gone. WARNING - have it in kinda open ground, it will smoke a tad, kinda like a peat fire - he he

call me if you have any questions - that is imperative - 813 286 8344

I think the ratio is one can (a pint, I think) in a gallon of gas. That's the mix I use anyway.
Dave

Since I'm on a recent rebuild I haven't done it in awhile - so thats why I kept saying follow directions