Long shaft to short conversion

Glassman87

Cadet
Joined
Jan 17, 2017
Messages
12
Ok new here and looking for some knowledge. I have a 1984 Johnson 140 hp (j140txcrd) it's a 25"shaft i got it real cheep. The power head and all is in great shape has perfect compression ect. I want to make it into a long shaft or 20" as I have no use for a extra long 25". I have a 1978 115 I can get for 250$ it's a Johnson 115 (115etl78c) my ? Is can I take my 84 140 power head and swap it on the 78' 115 midsection down. I've researched part numbers their is alot similar but not sure if it's as plug and play as I think.or if it's doable the drive shaft exhaust gasket and shift rod are all matching part numbers on omc but the exhaust housing adapter is diff part number. Any help would be greatly appreciated
Thanks in advance
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,306
Sell motor, converting to cash. Take cash and buy short shaft motor (converting cash to motor)

Not only is it the easiest way, it's also the cheapest.
 

Glassman87

Cadet
Joined
Jan 17, 2017
Messages
12
I only would have 300$ in the motor if the power head will swap and a decent 140 hp is hard to come buy been looking for over 2 years either lower unit trouble or needs new power head ect. If I sell it all I'm.back to months of searching and I have a need for the 140 this summer
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
What boat are you putting it on? Chances are it may have a rotten transom, rebuild it 5" higher.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
You could get a manual jackplate for $150 or so. That could lift the motor 5".
 

Glassman87

Cadet
Joined
Jan 17, 2017
Messages
12
It's going on a plastron 1996 and has a cherry transom and thought bout the jack plate but essentially I'll have a good lower unit and trim and tilt going this route and can sell for nearly the price of what I have in the whole motor. Was hoping to find a early or mid eighties motor but no luck and this 78 comes cheep!
 

Glassman87

Cadet
Joined
Jan 17, 2017
Messages
12
Just as a follow up I bought the mid section and lower unit it all.matches up swapped the long for short and in business. Removed the drive shaft from the short lower unit installed and rebuilt the long lower unit changed mid sections and shift shaft were in business. Have a functioning awesome 140 HP for 700$ and still have to sell the lower unit and long shaft parts so cheeper than selling it all and converting to cash to buy another motor!!!! Thanx for the help I went page but page and compared part numbers and subs theirs not a whole lot diff from 79 up
 
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