Prop for 140HP Johnson

[140hpjohnson]

Hello, I just purchased a 1979 140HP Johnson on a 19' Renkin bowrider boat. The motor does not have a prop on it. I will use boat mostly for fishing and relaxing on the river. Need help with what Prop to buy for it. I am not looking for anything special, alum is fine. Need size and pitch recomendations please. Hope this is enough info as I am new to this.

Thanks

 

[Dhadley]

Re: Prop for 140HP Johnson

The common answer would be the prop that puts the top rpm in the 5700-5800 range. Without knowing more about the set up we'll assume the motor is mounted all the way down on the transom and there is no jackplate. If so, you'll probably want to start in the 3 blade 17" range, maybe a 15" depending on expected load.

Obviously we're also assuming the motor is healthy and running correctly and the boat is in proper shape.

 

[Chris's CVX16]

Re: Prop for 140HP Johnson

Hmm. 140HP on a 19' bowrider.

Get a tach that works. You should be able to find decent deals on Aluminum and Stainless props on eBay if you are patient.

Your motor is a V4 gear case 13 spline shaft.

I would start with a 13" diameter by 19" pitch. Put it on and try the boat out. With you in it alone and about average for gear and fuel loads you should be able to spin into the 5700 range. If higher get a 21" pitch prop if lower get a 17" pitch.

When I got my motor it was propped for a lot heavier boat than mine and came with a 13 1/2"x15" OMC prop that was mangled. After a year of testing it I went thru 6 different props before I settled on 4 I really like. Yes 4. I have a ski prop, cruising prop and 2 speed props from 17" pitch to 23" pitch. But I also have a boat that is not on the "prop" charts.

Good luck.

 

[140hpjohnson]

Re: Prop for 140HP Johnson

So the more weight I am carrying the larger diameter prop? or vice versa?
Thanks for the info

 

[trendsetter240]

Re: Prop for 140HP Johnson

So the more weight I am carrying the larger diameter prop? or vice versa?
Thanks for the info

No the diameter is not really something you should worry about. Pitch is the measurement that you need to consider.

lower pitch props will increase RPMS and higher pitch props will decrease RPMS. (at wide open throttle). Think of pitch as a gear in your cars transmission; lower pitch = lower gear, higher pitch = higher gear.

As dhadley said, go for a 17 or 19 inch pitch prop to establish a baseline and go from there. You might get lucky and pick the right prop right off the bat! I like BRP aluminum props for an inexpensive option.

 

[kenmyfam]

Re: Prop for 140HP Johnson

My suggestion would be a 17" pitch 3 blade cupped to begin with. If it is over much then knock the cups off if close or exchange for a different pitch depending on findings.
I use a 14" X 17" on my outfit for beginner skiers and a 14" X 19" cupped (with some of the cup removed) for general usage. This one is ported.