Does pitch matter

dcslick

Recruit
Joined
Dec 1, 2008
Messages
2
Hello,

I need to replace a prop on a 1974 6 HP Johnson. According to the manual it tells me I need a 8 diameter x 7 1/4 pitch prop. My problem is that I was told that I can vary in pitch such as a 7 pitch and I was told I can not and I should get what the manual states. Does it matter on this size motor? Any thoughts?

Thanks!
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Does pitch matter

Sure it does. But 1/4" isn't going to be a killer.If you went to a 6 or an 8 it could create problems. It all depends on the boat and typical load.
Best way to pick any prop is with info from a tach and gps speed.The right
tinytach will work on your motor and any other 2 stroke 2 cylinder motor.
 

dcslick

Recruit
Joined
Dec 1, 2008
Messages
2
Re: Does pitch matter

Thanks Steeles for the reply. I have a 14ft aluminum boat that I will use the engine on, it will be mostly used to get around smaller lakes. So i should be good if i get the prop with the 7 pitch? If i dont use the correct pitch can it damage the motor?

Thanks again!
 

Matthew A.

Petty Officer 1st Class
Joined
Jan 24, 2006
Messages
232
Re: Does pitch matter

Pitch can be everything...Especially so if you're a ball player or a salesperson
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Does pitch matter

Small lake or large lake, big motor or small motor, the pitch of a propeller can indeed be the cause of poor engine performance (lugging) and can cause motor destruction. In your case 1/4 inch of pitch is not a killer. Too much pitch means the engine will lug severely and too little pitch means the engine will over rev. The proper setup is one that allows the engine to run at the manufacturers recommended wide open throttle rpm with an average load.
 
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