Maximum RPM of 18HP Johnson

[Trapaddict]

I have a 64 Johnson FD-18E 18HP Long Shaft Motor. It currently sports a 9 1/4 X 11 Prop. With me, my three small kids and our fishing stuff, it pushes my 14 foot Mirro Craft along very well. Problem is that I cannot get the thing to troll very well. Too fast at idle for most of what we fish for. I am considering replacing it with a prop that is 8 3/4 X 9 to help with the trolling speed issue. My concern is over revving the motor at full throttle with a smaller prop. Does anyone know What the book say the maximum RPM for my motor should be?

Jeff

[rudetech1]

The horse power was rated at 5000 rpm. I would stay in that area, It's not a spring chicken. I had a 60' model with a Brass prop that would just whip the pants off those newer 20 horsepowers. I tried to troll but gave that up pretty quick. But wide open, she was a mean little *^%#!