Speed on a 67 Johnson

[Froggerman]

I have a 6hp 67 Johnson and it has a 2 blade prop on it.
Will putting a 3 blade prop on it make a difference in speed?
Also there is a knob on top that is for High idle im thinking. It seems too do much of nothing when I turn it, while running wide open. It will shut down if I turn it clockwise all the way. Im assuming im cutting off the fuel.
So I guess it does something LOL.
but shouldnt it rev engine some when I hit the peak point or proper spot?
Or shouldnt the High engine idle change up or down while I turn it?

Thanks for your comments
Wally

 

[tashasdaddy]

Re: Speed on a 67 Johnson

the word is IDLE> slow speed. it is there so you can set the stop point on the slow speed, like when you are trolling. you will get more power from a 3 blade, but not necessarily speed.

 

[1946Zephyr]

Re: Speed on a 67 Johnson

I never seen a fuel shut off on one of these

That screw you see is probably the low speed needle and those should be set at 1 1/2 turns out from bottom. once you set the screw, then place the knob back on the screw in the center position, from the stop and that will allow you to turn it a 1/2 turn either way till it stops. Most likely on that, there is a stop at the 12 o'clock position, therefore place the knob back on, so the stop on it, is at the 6 o'clock postion.