Standard Prop size and Pitch for 1970 25hp Johnson

fishonboat

Seaman
Joined
Jun 23, 2003
Messages
52
I just picked up a 1970 Johnson 25hp outboard model number is 25R70E. It's a little project I'm playing with. The Prop that was on there is pretty much shot. Also the previous owner must of ran out of Shear pins so he drilled hole through the prop and ran a stiff piece of wire from one side to the other. Anyway I'm trying to find the standard size prop and pitch that was put on this outboard. It's going on a 16' fiberglass V-bottom skiff. Boat is very light. Also if anyone has one of these and they have had and problems that I should know about or let me know if it has been a good motor. Thanks
 

Paul Moir

Admiral
Joined
Nov 5, 2002
Messages
6,847
Re: Standard Prop size and Pitch for 1970 25hp Johnson

It's a guess naturally, but probably 9x10" would serve you well. Any idea what the rig weighs or how fast it went on the old prop? I take it you've got no tach.<br />There is no 'standard size' as such, the range is 9" to 11" for most boats, but props are available outside that range. I'm thinking 10" so it'll rev freely.<br />Any numbers on the old prop? They might be underneath the thrust washer.
 

fishonboat

Seaman
Joined
Jun 23, 2003
Messages
52
Re: Standard Prop size and Pitch for 1970 25hp Johnson

I have a 15hp on there now and I just bought this 25hp to replace it. It's a tiller so there is no Tach. The total weight with crabbing gear and two people is probably around 600-700 lbs. I couldn't find any numbers on the old prop indacating the size and pitch but I will look again tonight. I found some props for my motor on iboats web site and the range is any were from 9x7 - 9x12. Some of these being 9.25 Diam. I guess 9x10 would fall some were in the middle.
 

Paul Moir

Admiral
Joined
Nov 5, 2002
Messages
6,847
Re: Standard Prop size and Pitch for 1970 25hp Johnson

Yeah I'll stick with 10" 3-blade on that. Don't worry about the numbers on the old prop unless your curios - I got the impression the motor had been part of the rig. Don't worry about the diameter either - that's really the prop manufacturer's business.<br />In 1970 they shipped them with 10" props, with 9" being available as an option for heavy boats. If you were light enough a 11" might make sense, but a 12" is really for race boats (+30mph). :)
 

alderman

Petty Officer 2nd Class
Joined
Aug 11, 2004
Messages
116
Re: Standard Prop size and Pitch for 1970 25hp Johnson

I have a 1971 rude 25hp it has the standard prop 9x10 the optional was a 9x9 both three blades.<br />Good luck<br />Ray
 

fishonboat

Seaman
Joined
Jun 23, 2003
Messages
52
Re: Standard Prop size and Pitch for 1970 25hp Johnson

Thanks. I will probably go with the 9x10 then.<br /><br />Do you like your 1971 Evinrude? Has it been a good Motor for you? Any problems with it?
 

alderman

Petty Officer 2nd Class
Joined
Aug 11, 2004
Messages
116
Re: Standard Prop size and Pitch for 1970 25hp Johnson

I have had it a couple of seasons now, bought it used in garage sale. It has been a pain at times but I now have all (I hope) old problems worked out. Previous owner diden't do much in way of maintance. Carb rebuilt, water pump, new plugs and wires, and lower unit sealed. Runs vary vary good now and pushes my 14 foot starcraft up and down the Missouri river great. I bought my new prop 9x10 hear on Iboats, good deal as the old one had a spun hub, I keep it now for a spare.<br />The old John/Rude motors of this age seem to be vary good with just some maintance and a decarb once a year, keep us posted on yours.<br />Ray
 
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