Johnson Prop Question

[CJY]

I have a 1989 Johnson 70 hp motor(3 cyclinder). I bought it from a private person and I have reason to believe the prop may not be original for the motor.

The prop is a 13 3/8 x 17 alum. Is this correct for this motor?

Thanks in advance for any help.

One more add on Q. If I put a stainless 13 3/4 x 17 on my boat, what diff will this make?

 

[Silvertip]

Re: Johnson Prop Question

You should post prop questions on the "Prop Forum". But since you posted it here you need to know first off that there is no such thing as a "standard" prop for outboards that are generally larger than about 40 HP. Why? Because the prop that must be used depends to a great extent on the type of boat, its weight, and the load it will normally carry. In other words if the engine is installed on a work boat, it will require a different prop than if the engine is installed on a racing shell or recreational boat. The proper prop is one that allows the engine to rev at the upper end of its recommended wide open throttle rpm band with a normal load. Since you do not have that data, (max speed and RPM) we can't tell you for sure if its the right prop for your boat. I can tell you it is in the approximate range. Go to the Frequently Asked Questions at the top of this forum and scroll down to the topic dealing with prop selection. It tells you what you need to determine what prop changes are necessary.

 

[CJY]

Re: Johnson Prop Question

You should post prop questions on the "Prop Forum".

Sorry, and thanks.