Jack plate or powerhead swap?

egscharf

Seaman Apprentice
Joined
Dec 2, 2012
Messages
30
I have a 1990 90HP that runs great, but is too short for my boat. I also have a 1997 115HP with a blown powerhead, but is the perfect length.

My question is can I swap the powerhead from the 115 for the powerhead on the 90?

If not, will a jackplate work?
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Jack plate or powerhead swap?

Go to shop.evinrude.com and compare part #'s and diagrams.
 

egscharf

Seaman Apprentice
Joined
Dec 2, 2012
Messages
30
Re: Jack plate or powerhead swap?

Ok I examined the parts diagrams for both. The exhaust housings, exhaust housing gaskets, and exhaust housing adapter plates are the same for both. The only difference is the adapter plate housing gaskets. I don't see a difference visually, but the part numbers are different. So my take is that if I leave the adapter on the 90 when I swap it to the 115 leg, everything should match up.
 

egscharf

Seaman Apprentice
Joined
Dec 2, 2012
Messages
30
Re: Jack plate or powerhead swap?

Hmmm, on second look, each engine has a different crankshaft and driveshaft. My worry is that the 115 driveshaft might not fit the 90 powerhead.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Jack plate or powerhead swap?

It is possible the drive shaft lengths are different between "91 and up.
 

Outsider

Lieutenant Junior Grade
Joined
Apr 24, 2007
Messages
1,022
Re: Jack plate or powerhead swap?

While I don't know for sure, I'm betting a straight swap won't work. But I'm having trouble visualizing your plan. The 90 runs great but you want to swap the power head out with a rebuilt 115 if it'll retrofit, the 115 is the correct length for your boat but you want to go with a jack plate for a motor with incorrect length? Alternate suggestion - sell the 90 and use the proceeds to help fund a conventional 115 rebuild. You will have a rebuilt power head, the lower unit will be the correct length, and you'll have 25 more HP ... :happy:
 

egscharf

Seaman Apprentice
Joined
Dec 2, 2012
Messages
30
Re: Jack plate or powerhead swap?

I would like to put a 1990 90 HP Powerhead on a 1997 Johnson leg.

I'd rebuild, but I can't even tighten a head bolt to minimum spec without it stripping out. I can't imagine what other major issues I might face, but if worse comes to worse, maybe I'll do just that.

Honestly though, I'd probably prefer to go with the jack plate.
 

Outsider

Lieutenant Junior Grade
Joined
Apr 24, 2007
Messages
1,022
Re: Jack plate or powerhead swap?

Ahhh, now I see, 90 for 115 and not 115 to 90 frame. Still be surprised if it retrofit ... :facepalm:
 
Top