johnson 85 hp prop question

[Chrism77]

I have a 70 Johnson 85 HP that is a v4. The prop I have is 13-1/4 by 15 I have read that a 17? pitch is what it should have. There is a new prop a guy has that is 15 x 17 part number 391200 for sale cheap.. is this to much prop for me?

 

[steelespike]

Re: johnson 85 hp prop question

My information indicates the 391200 is for a V4 with a V6 gear case.
I think your 13 1/4" prop is intended for a V4 gear case.
Your prop selection would depend on your setup.
We need your boat information and your wot rpm and gps speed with your 15" prop.

 

[Chrism77]

Re: johnson 85 hp prop question

Let me clarify I have the 13 1/4 prop on my v4 now. I would like to replace the prop because it has some dings and the local shop wants 85 to balance it. The 391200 is one that is for sale in town cheap. My boat is a 70 glastron tri hull. I don't have a working tach and have not gotten a speed because I have only had it on the water one time

 

[steelespike]

Re: johnson 85 hp prop question

I understand. The part number you gave us 391200 indicates it is for a V4 with a V6 gear case. It won't fit your motor.
"your 13 1/4 prop is intended a V4 gear case" thus your gear case is a V4 and the 391200 won't fit.
A induction tach like the Tinytach will work on almost any motor land or sea. Just be sure to tell them its for an outboard.
For your motors health and performance you need to be sure your prop is right. The 15 may be fine.
A carefully done gps speed lightly loaded we may be able to guess at your rpm.Not a good idea but better than no information.
A description and size of your boat will help valuate your setup.

 

[Chrism77]

Re: johnson 85 hp prop question

OK..we are going out wed.. I will try to get the info then. The boat is a 17 food glass boat set up manliy for fishing.12 gallon fuel tank and 2 to 3 people