1984 Mercury 25 HP Shaft Conversion

moxieman

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Apr 26, 2006
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Does anyone know where I can get a conversion from short shaft 15 Inches, to long shaft 20 inches... Does this really need to be done if I plan to put the motor on a Lund 14 with a 20 inch transom... I have it on my Lowe with a 15 inch transom...
 

Don S

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Re: 1984 Mercury 25 HP Shaft Conversion

You will need the extension kit, without it, you wouldn't be able to go very fast as the prop would be behind the transom and would cavitate when trying to speed up.
Here is one place you can get them. They may even be here at iboats, but I sure can't find em. You will also need your engine serial number.

http://www.marineparts.com/partspages/Accessories/acc8.htm
 

moxieman

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Apr 26, 2006
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Re: 1984 Mercury 25 HP Shaft Conversion

Just went out and measured my transom, and it appears to be 16 inch which is odd, and my cavitation plate is two inches below the transom, which makes it and 18 inch shaft.. That doesn't sound right, but will it work work with out the conversion? Also will a
Doel-Finn help?
 

Don S

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62,321
Re: 1984 Mercury 25 HP Shaft Conversion

If the cavitation plate is below the bottom of the boat, you should be fine. You could actually shim the motor up some
 

moxieman

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Apr 26, 2006
Messages
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Re: 1984 Mercury 25 HP Shaft Conversion

Well, on my old boat it would be Ok, I don't know if your are familiar with the Lund 14 SSV boats at all, and would an 18 inch to the cavitation plate be ok? Does a Doel-Finn help correct this?
 
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