1966/1967 Evinrude 18hp convert short to long shaft

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SuB8HaVeN

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Hello, I have a 1967 Evinrude 18hp that I've been having ridiculous carburetor trouble with. When you pump fuel to it, it will flood out of the overflow and discharge nozzle. I replaced the float, needle, and needle seat with genuine OMC parts and have adjusted the crap out of it. It works fine by mouth and compressed air, but fuel keeps getting by the needle. So I found another 1966 18hp parts motor that was complete in "running" condition. The carburetor is currently sitting in chem dip waiting to be put back together and go on my good motor.

Now here's my question. The 1966 18hp (the parts motor) is a long shaft. My 1967 18hp (my good motor) is a short shaft. I'd like to install the long shaft on my good motor as I'm thinking about buying a 30' sailboat with a bad inboard, and would need a kicker for the time being. I've begun tearing apart the lower unit on the long shaft motor, but can't seem to figure out how to disconnect the gear shifter lever. I've pulled the lower unit off to the point that the gear shifter is in gear and I have about an inch to peek inside. I've worked on a few smaller Johnsons in my time that had a bolt and a piece that connected the lower shift rod from the upper, but it seems to be all one piece from the midsection all the way to the lower unit. How does this bad boy come apart? Secondly, what would be involved with installing the long shaft onto my other motor? Is it just a matter of bolting it on? What if I wanted to use my lower unit on my good motor (as it is in much better condition) with the long shaft extension plate? Thanks!
 

tx1961whaler

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Re: 1966/1967 Evinrude 18hp convert short to long shaft

There should be a little plate on the side of the midsection where you can get at the shift coupler.
5 things different about the long shaft:
the 5-inch extension housing
longer mounting bolts
the shift rod connector
drive shaft
water tube
 

jasper60103

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Re: 1966/1967 Evinrude 18hp convert short to long shaft

As tx1961whaler said, you can swap a few parts to convert that short to a long.

ext_kt.jpg
 

SuB8HaVeN

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Re: 1966/1967 Evinrude 18hp convert short to long shaft

Well that solves that, thanks for the info guys! What does swapping the driveshaft involve? Do I need to pull the powerhead to do that?
 

tx1961whaler

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Re: 1966/1967 Evinrude 18hp convert short to long shaft

Well that solves that, thanks for the info guys! What does swapping the driveshaft involve? Do I need to pull the powerhead to do that?
No. The driveshaft comes out when you take off the lower unit. The water tube is the hardest part of this conversion operation, as sometimes the old one doesn't like to come out after 40 years.
 

SuB8HaVeN

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Re: 1966/1967 Evinrude 18hp convert short to long shaft

Sorry, forgot about that. Is it too difficult to swap the driveshaft with the lower units? I'd like to use my existing lower unit as it's in much better condition but I'd have to swap out the driveshaft with the longer one.
 

BigB9000

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Re: 1966/1967 Evinrude 18hp convert short to long shaft

The water tube is the hardest part of this conversion operation, as sometimes the old one doesn't like to come out after 40 years.

Agreed.

I found if you get something that clamps to the tube, it can be removed pretty easy. I use a tubing flaring set.

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