prop pitch for 56 johnny

[56 rude]

Hi guys and gals,i have a 14 foot 7 inch cedar-strip boat with a 1956 tiller drive johnson that ive just redone hanging on the back.This boat is rated for 35hp max.Ive never had it out yet but today is the big test day on the water so id like some suggestions on where to start with pitch.Ok,this motor has a hard to find vari-pitch prop that can mechanically adjust from 9p to 15 p,so being that the boat weights 275 alone add yours truly at 235 plus 5 gallons of gas and anchor etc,where should i start?Ive got it set right now at 11 1/2 p.Also i might add my one concession to modern times is a set of nauticus trim tabs.

 

[steelespike]

Re: prop pitch for 56 johnny

You didn't say your hp.
I would say the 11 1/2 is a good place to start even if its a little light
you can just throttle back a little.
You shouldn't run without a tach.Not possible to get the ideal setup
without rpm and speed.You could get a tinytach reasonable,easy hookup
and will work on any 2cyl 2 stroke without regard to stator poles.
Your vari pitch prop is nice to get an idea of the best pitch but needless to say won't be as good as a dedicated prop.

 

[56 rude]

Re: prop pitch for 56 johnny

You didn't say your hp.
I would say the 11 1/2 is a good place to start even if its a little light
you can just throttle back a little.
You shouldn't run without a tach.Not possible to get the ideal setup
without rpm and speed.You could get a tinytach reasonable,easy hookup
and will work on any 2cyl 2 stroke without regard to stator poles.
Your vari pitch prop is nice to get an idea of the best pitch but needless to say won't be as good as a dedicated prop.

Thanks for the reply,had serious issues yesterday with the motor(30 hp) so im going to my other one which is a 1970 33 hp rude with tiller drive.My big project slash rebiuld to like new one is going to be my 1957 18 hp johnny.Im going to have 3 of the buggers so i should be alright for parts,lol.Will have to check up on the tiny tacs.

 

[jay_merrill]

Re: prop pitch for 56 johnny

I've never owned a '56 Bigtwin, so I'm not sure of the shear pin location on the prop shaft, but if its in the same location as the 33hp, your vari-prop should work on the 33hp too. Since there isn't much difference in power between the two motors, tweeking the vari-prop should give you an idea of what pitch to use for the '56.

I also agree that a Tiny Tach would be a great tool in helping you get the right setup. I had a pair of them on my '58 Bigtwins, so that I could "marry" the throttles to get the same rpm settings on both engines for cruise. The two stroke model would obviously be the one to get, but a four stroke model wiil work - it will just double the true rpm value. Its also nice to have the four stroke model because you can use it on something else if you don't want to do a permanent installation. Since I'm not using the Bigtwins anymore, one of mine is now on my lawn mower and the other is on my portable generator!


http://www.tinytach.com/tinytach/index.php

 

[Draven1772]

Re: prop pitch for 56 johnny

This is where I went to check my prop pitch: http://www.psepmarineparts.biz/store/evinrude_johnson_propellers.htm