Going up in size and down in pitch???? What will happen?

cturboaddict

Petty Officer 1st Class
Joined
Aug 29, 2010
Messages
224
Ive got an 1971 85hp Evinrude on an 1972 18' Sidewinder...
Currently on the boat i have an 12 3/4x21 aluminum prop...
I found someone selling a 14.25x17 stainless prop...

If i purchased this what should i expect to happen? And is it worth it at the bargain price of $125 used? Its a michigan prop...
Thanks
 

cturboaddict

Petty Officer 1st Class
Joined
Aug 29, 2010
Messages
224
Re: Going up in size and down in pitch???? What will happen?

Actually no i dont.....
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: Going up in size and down in pitch???? What will happen?

You need pitch to go fast! dropping down 4 pitches will most certainly drop the top speed--even if the prop diameter fits on your lower unit. The larger diameter is for displacement hulls like a pontoon. In your case, if you have a planing hull and the engine runs at its correct RPM, you will be unhappy with the result, so unless you want to use it as an emergency prop, no, it is not worth the 125. (to you)
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,366
Re: Going up in size and down in pitch???? What will happen?

Ayuh,... I would expect to see about 1000 More rpms,...
If the prop will even fit on the motor.... Which it probably Won't....
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Going up in size and down in pitch???? What will happen?

A 14 1/4" diameter prop is for a V6 style gearcase and is too big for a V4. The correct size for your V4 will be in the 13 1/2" diameter range, + or - a bit.
 

cturboaddict

Petty Officer 1st Class
Joined
Aug 29, 2010
Messages
224
Re: Going up in size and down in pitch???? What will happen?

Thanks... I appreciate that.
You guys rock... Back to work!
 
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