4-Blade Prop, 1972 65hp Johnson?

[Chaz1]

Re: 4-Blade Prop, 1972 65hp Johnson?

Chaz -- prop pitch is measured in inches of pitch -- not degrees of pitch.

What can I say? As you can see, I'm only a cadet!!!!:redface:

 

[jay_merrill]

Re: 4-Blade Prop, 1972 65hp Johnson?

I just picked up a used PowerTech 3 blade, 15" pitch, cupped SS prop from my local OMC dealer. The wheel had been sitting around his shop "forever" and is in very good condition. I didn't ask, but it looks like it had gone to the prop shop after coming off a motor and, for some reason, the customer never took it back. I have been doing business with this dealer for years and he was anxious to move it, so he sold it to me for $50. From what I have learned by surfing the net, PowerTech props are very good props and this model retails for well over $300.

I tested it on the boat today and it runs at about 100 - 125 rpm higher than a 15" pitch aluminum prop of the same diameter. Top end seems to be nearly identical to the aluminum prop but it seems like I am using less throttle to maintain my typical cruise rpm of about 4200 - 4400 rpm. Speed in that range seems to be slightly higher - not enough to get excited about really, but there does seem to be a difference.

I think this prop is going to give me the things I was looking for and the price sure can't be beat!

 

[Chaz1]

Re: 4-Blade Prop, 1972 65hp Johnson?

Jay I see that you have a tach on your motor. I am also interested to put one on my boat and was wondering if you did that yourself or if it was already on your boat. Any help wpould be appreciated

 

[jay_merrill]

Re: 4-Blade Prop, 1972 65hp Johnson?

I have a Teleflex tach in the dash. You should be able to do the same easily.

Once you get the tach mounted in a convenient location, open your throttle control unit to run wiring to your tach. Color codes/hookup to your tach are as follows"

Gray = Send
Purple = Ign
Black = Gnd.

I grounded my tach to something else just to avoid having to run three wires into the control unit. If the tach that you buy is lighted, there will also be a place to run a wire (I would use red) off of the switched side of your running light switch. There is also a rotary dial on the back of the tach - set it to "6P."

 

[Chaz1]

Re: 4-Blade Prop, 1972 65hp Johnson?

I have a Teleflex tach in the dash. You should be able to do the same easily.

Once you get the tach mounted in a convenient location, open your throttle control unit to run wiring to your tach. Color codes/hookup to your tach are as follows"

Gray = Send
Purple = Ign
Black = Gnd.

I grounded my tach to something else just to avoid having to run three wires into the control unit. If the tach that you buy is lighted, there will also be a place to run a wire (I would use red) off of the switched side of your running light switch. There is also a rotary dial on the back of the tach - set it to "6P."

Hey thanks Jay. I think I'll go tach shopping on the net this morning.

 

[jay_merrill]

Re: 4-Blade Prop, 1972 65hp Johnson?

I have been running the boat with the SS prop for a bit now and have to thank Mark for pointing me in this direction. Although I stayed with a 15" wheel instead of going down to a 13", I am very happy with what I am getting out of this setup. I was also wrong about top end - I have been playing with different power settings and I am getting increased speed across the range, including top end.

Now, if I can get the same price on that 14" pitch SS wheel that my dealer has for when I want to load the boat up a bit ....