Making a 78 johnson 9.9 long shaft to short shaft.

M

mchin

Petty Officer 2nd Class
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Jun 15, 2007
Messages
195
I have 2 johnson 9.9's, one a 74 (short shaft), the other a 78 (long shaft w/ elec start). I'd like to take the leg and lower unit of the 74 and put it on the 78, this way I'd have a 9.9 short shaft with electric starting. I was looking at the diagrams, and it seems I'd have to swap exhaust tubes, drive shafts shift linkage and that's about it. Am I missing anything, has anyone done this swap? While both have great compression, the 78 has 120 on each cylinder and has less wear. Any help or advise would be great.
thanks
mc
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
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51,019
Re: Making a 78 johnson 9.9 long shaft to short shaft.

drive shaft, exhaust, water tubes. may be easier to move power head.
 
R

Rick.

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Jul 30, 2006
Messages
3,740
Re: Making a 78 johnson 9.9 long shaft to short shaft.

The water tube also. Lots of posts about doing this conversion but not many ever report after the job is done. That leads me to think they haven't had any problems. Just go over the parts list with a fine tooth comb to make sure the parts are swapable. I'm pretty sure you will find it's a straight forward project. 120 is fantastic for any motor let alone one that is almost 30 years old. Best of luck. Rick.
 
M

mchin

Petty Officer 2nd Class
Joined
Jun 15, 2007
Messages
195
Re: Making a 78 johnson 9.9 long shaft to short shaft.

thanks for the suggestions. I did consider a head swap, I've done it before, but it was all with older engines. I'll try to make notes and all, if I can I'll post a how I did it thread.

mc
 
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