9.9/15 hp Shaft Conversion

[scout-j-m]

Yesterday I bought a pair of running 1982 Evinrude outboards. One is a 9.9 hp long shaft and the other is a 15 hp short shaft. I'd like to swap parts and reverse the two shaft lengths. I already have a couple small short shaft Evinrudes and am in the process of ordering an Alumacraft 1648 flat bottom with the short transom. I also am wanting the 9.9 to be the short shaft between these two because a couple local lakes have a 10 hp limit.

Looking at the exhaust housing diagrams between the two models, both appear to have the exact same part numbers for the exhaust tube and upper shift rod. The 9.9 has a longer lower shift rod though. Theoretically should I be able to just swap out the 5" leg spacer and the two lower units (in order to avoid removing the lower shift rod and driveshaft) and keep the exhaust tubes and upper shift rods in place? If so that seems like it would be a very simple procedure.

And while on the subject...I may decide to swap parts to mod the 9.9 up to a 15 hp. I know the carb and the reed valve shims are required but after researching on here and Leroy's Ramblings I was under the impression the 15 hp model in 1982 had the tuned exhaust, however, the parts lists show each model as having the same part number. Is it true that the 1982 does not have the tuned exhaust?

 

[racerone]

Fact------The shift rod can be screwed out and replaced without any risks.------The driveshaft pulls out and can be replaced without any risks.----Easy as can be.

 

[scout-j-m]

Thank you.

Any insight on the exhaust tubes for this year?

 

[interalian]

Or you could put the cowl from the 9.9 on the 15...

 

[scout-j-m]

Or you could put the cowl from the 9.9 on the 15...

True that. But even though one of my reasons for doing the conversion would be if the serial plate was ever checked, both motors have some minor issues that will need some swapping of parts. I don't know if any would justify removing the power head but they may as I dig deeper into them. I do know the 15 hp's upper shock mount is wore slap out though. I guess for now, I can just use both as is until I can boat test them more and iron out the issues. But like I said, they both run well and will get me from point A to B. Hopefully I can consolidate the best parts into one motor and sell the other. I probably didn't get the best deal in the world paying $500 total for the two but around where I live (near a HP restricted lake) 9.9's and 15's are at a premium and one in decent shape and good running condition would bring $500 alone.

Sorry for the story lol. Was gonna delete if I typed it up but it took me too much time to type it all out!

 

[oldboat1]

See if the water tubes can be pulled from the grommets on the '82s (think they can). If that's possible, probably can easily switch the shorter 15 tube to the 9.9, and then bolt up the 15 l.u.

 

[flyingscott]

See if the water tubes can be pulled from the grommets on the '82s (think they can). If that's possible, probably can easily switch the shorter 15 tube to the 9.9, and then bolt up the 15 l.u.

NO !!!. Do not try pulling on them they are flared at the top if you pull on them will damage the tube or the grommet. The only way they come out is to remove the exhaust tuner off the powerhead. That means you have to pull the powerhead.

 

[oldboat1]

Probably right, unfortunately. But If you don't want to pull the powerhead(s), can cut five inches off the longer tube, then bolt up the other l.u. Save the piece you cut off for future reference. I shortened the shaft on a '90 9.9 that way, and it worked fine.

 

[scout-j-m]

Oh ok...so both models have the same length exhaust tube but the water tube (output line from the water pump I'm assuming?) is longer on the 9.9 long shaft? If cutting the water tube will work, I can try that. It will allow me to swap the lower unit with the short driveshaft and shift rod back and forth between the two motors while I get familiar with them. I can worry about a new longer tube later on I guess.

 

[flyingscott]

It is not a big deal to cut the water tube 5" evinrude makes a 5" extension that slides over the water line so you can convert back and forth easily. 0306563 is the part# can get it for less than $10 double check the part# but pretty sure that's it

 

[scout-j-m]

It is not a big deal to cut the water tube 5" evinrude makes a 5" extension that slides over the water line so you can convert back and forth easily. 0306563 is the part# can get it for less than $10 double check the part# but pretty sure that's it

Awesome. This sounds like the best path for me for the time being then. I appreciate all of the help.