I have a 20' pontoon that I recently installed a 1977 Johnson 70 on to replace the 35hp that came with it and I am trying to get it set up properly, or as close as possible anyway.
It did not seem to give me as much extra speed as I thought doubling the HP would give me. (not expecting it to be a speed boat either).
I bought a 13-3/4" x 13 prop as recommended by the local prop shop. I just raised the motor on the transom 1", because it seemed to sit too low in the water and I trimmed it up 1 space.(no trim & tilt just manual)
This weekend I took it out and it seemed to have picked up some speed and ran great, but I hooked up my temporary tach and at WOT, I was only at 2000 rpm's. This motor's max rpm is 5000. So assuming that my tach was accurate, where do I go from here? Would trimming the motor up one notch have caused me to lose rpm's?
It did not seem to give me as much extra speed as I thought doubling the HP would give me. (not expecting it to be a speed boat either).
I bought a 13-3/4" x 13 prop as recommended by the local prop shop. I just raised the motor on the transom 1", because it seemed to sit too low in the water and I trimmed it up 1 space.(no trim & tilt just manual)
This weekend I took it out and it seemed to have picked up some speed and ran great, but I hooked up my temporary tach and at WOT, I was only at 2000 rpm's. This motor's max rpm is 5000. So assuming that my tach was accurate, where do I go from here? Would trimming the motor up one notch have caused me to lose rpm's?
