Evinrude 9.9 (1979)

[bannerd]

I have a Evinrude 9.9 model number (model) 10924B, made in 1979. I'm looking at getting a 18HP motor for about 2,000$ but a friend of mine says that I might be able to just upgrade the carburetor from a Evinrude 15HP? I've been searching the internet looking for an answer and I believe all I have to do is swap my carb out with a 15?

Also, since OMC is out of business does anyone make these anymore or is it rare they'll pop up on ebay once in awhile? I did talk to my evinrude dealer and they're against it but I could pull schematics and put one together.

Thoughts?

[CATransplant]

Ask your Evinrude questions in the Johnson/Evinrude section, not in the Other Outboards section. You'll get better response in the correct section of this forum.

[jawalpole]

google leeroys ramblins and he will break it down for you. Yes you can make it a 15 hp but you also have to replace the exhaust tube but yeah way cheaper than $2000.

[dazk14]

The conversion you speak of is done all the time. Usually, just the carb is replaced with a used 15hp of that era. Ebay will often have them@~$135.

Probably adds more like 2.5 hp when revved up.

If the 18hp your looking at is late 80's or newer it will have much more power than a 79 ~15hp. What are the specifics of the 18hp, how many cu.in. motor?

[raczekp1]

i have 83' 9.9 johnson,i'm the owner .
now i'm fixing 15hp johnson 79' model.
compering this two motors i can say the diference is:
1.different carb(throath size),
2. leaf valve stops contain spacer(shrim)aded,
3.powerpack has different number(9.9 can have rev limiter, but i'm not sure)

[OptsyEagle]

Many times the throttle cams are different as well. I think they use a slightly different spark timing to the various throttle settings and it is done with a different throttle cam design.

Makes sense if you think about it. If spark advance is different at 2000 RPM then it is at 4000 RPM, it makes sense that a carb with a different throat will have a considerably different RPM at all the various twist grip settings and hence your throttle cam controlling this will need to be different.

[raczekp1]

timing plate is the same(throttle cam is the same) but powerpack is a different.

[OptsyEagle]

Hmmm. I know the 1974 & 1975 models have different throttle cams on their 9.9Hp and 15Hp motors respectfully, but of course they use points and condensers and not powerpacks. Does the powerpack change the spark advance at the different RPM ranges? I was under the impression that all it did was set the initial timing and of course the timing plate/throttle cam did the advance.

If this is the case, does it make sense that a 9.9Hp and 15Hp would have the same spark advance? Am I missing something?