58 7.5 johnson aftermarket props?

[kbert1171]

can anyone tell me where i can find an aftermarket 3 blade prop for my 58 7.5hp johnson (AD-12)? looking for something to give the ol girl a little more power. thank you.

 

[jimmbo]

More power? As in higher top speed? Quicker acceleration? What rpm is the engine currently getting at full throttle? What is the engine WOT rpm range?

 

[kbert1171]

Top speed is what I had in mind. I have no idea what the full throttle rpm. And honhonestly, I wouldn't know how to find it. Nor do I know what WOT means.
I'm pretty new to this. I read a forum a while back about someone using an aftermarket prop (3 blade from Michigan prop, I believe) and I thought I'd like to check it out.

 

[Chinewalker]

Honestly, if you need more power, I'd go with a larger motor. The 7.5s are great running motors, but a powerhouse they are not. If its the difference between planing off a small tinny and not planing off, it might make a difference, but if you've got a large boat full of duck decoys, hunters and gear, you'll likely not notice a huge difference. What are you running the motor on - hull type and typical load?

 

[kbert1171]

14'X36" Jon boat. The wife, me, tank, battery, poles tackle box, anchors. It's a pretty good load for it. Searching for a larger upgrade. But in the meantime...

 

[jimmbo]

I doubt a prop change is going to give you any great change in speed. However if the current prop is running the engine outside its recommended RPM range, there will be a speed increase one the engine is back in the range, The idea for max speed is to prop it so the engine runs at the hp where peak HP occurs. Running on either side of that peak, but still within the WOT range does result is a slightly lower top speed, but not as great as running outside of the WOT range

 

[kbert1171]

I'm not expecting a giant leap in speed, just a little more and a new outboard is not in the budget right now. Just looking to optimize what I have, until such time as we can afford a better fitting boat.I do want to thank you all for your input. I do appreciate it.