NewtRoberts
Cadet
- Joined
- Feb 19, 2024
- Messages
- 15
Carburetor comparison: look inside the throat and difference is obvious. A 9.9-HP carburetor throat measures 0.625-inch and the 15-HP carburetor throat measures 0.875-inch. There were three difference carburetors offered over the model years (early, mid, and late model production)I just took this off a 1979 Johnson 9.9 . Not sure if this is a 9.9 carb or 15 carb.
I read this on Leeroy’s Ramblings as well.Difference Between the 9.9 & 15hp : When they designed this series of motors, they designed it as a 15 hp and then detuned it with a different carburetor for the 9.9. When the 9.9hp and 15hp came into being in 1974 and up thru 1978, the only real difference between the two motors was the carburetor. In 1979 they added a shim, part #325038, (one for each cylinder), behind the leaf valves and under the stop plate for the 15 hp, apparently to allow leaf valves to open up more at higher RPM, giving the motor more fuel in the air mixture.
The owners manual indicates that the operating range RPM for the 9.9 to be 4500 - 5500 where for the 15hp it is 5500 - 6500 RPM. So where the 15hp gets it's power over the 9.9 is that the carburetor allows more fuel/air to increase the RPM by 1000 which equal the extra power.
Definitely do not want to sell it! I’m just glad that I have it and do not need to buy one! Phew at those prices!Don't sell that thing! They fetch a good price for a reason. You'll want it for your motor.
OMC built both Evinrude and Johnson motors. The 9.9 is just a derated version of the 15 to comply with lakes that have a 10HP limit restriction without retooling. who knew.I read this on Leeroy’s Ramblings as well.
as far as older outboards, dont we call that patina. lolUnderstandable that you get excited about this motor find.----I see a corroded motor that may have a lot of bolts that will break if you try to do needed maintenance.----Evaluate this motor before spending a lot of $$$ on it.
Understood. I plan to tear it all down before actually ordering parts and gaskets for it. But even if it doesn’t pan out to be a good motor, at least I got a 15hp carb out of it for $100.Understandable that you get excited about this motor find.----I see a corroded motor that may have a lot of bolts that will break if you try to do needed maintenance.----Evaluate this motor before spending a lot of $$$ on it.
The bolts I have turned so far didn’t seem bad. Though, I haven’t tried power head bolts yet.Understood. I plan to tear it all down before actually ordering parts and gaskets for it. But even if it doesn’t pan out to be a good motor, at least I got a 15hp carb out of it for $100.
if that profile pic is you, i have total confidence you are up to the task, looks to me you have been working on anything and everything and have total confidence you will figure it out. A country boy will survive. we will assist anyway we can. ( btw i am a redneck ) jmoThe bolts I have turned so far didn’t seem bad. Though, I haven’t tried power head bolts yet.
start simple, spark, fuel, rotten hoses, clean carb, she if she fires up ( for about 5 seconds ) then you can go deeper into it. impeller, etc etcJust went out to the garage and gave every bolt that I could reach easily with a 7/16 and 1/2 wrench a turn and they all came loose without much pressure. As far as corrosion goes, I don’t see much on it. There is some rust on the top of the power head. But the rest of it is just very dirty. This motor sat in a barn for 12 years. On the dirt! Hopefully it’s a fixer upper but if not, oh well. When real tear down work begins, I’ll be starting a thread dedicated to it. And hopefully that will turn into rehabilitating this old girl and getting her back in the water.
I posted in another thread about the motor earlier today that I did get her to turn over and putter for a moment. Which gave me hope.start simple, spark, fuel, rotten hoses, clean carb, she if she fires up ( for about 5 seconds ) then you can go deeper into it. impeller, etc etc
That is me.if that profile pic is you, i have total confidence you are up to the task, looks to me you have been working on anything and everything and have total confidence you will figure it out. A country boy will survive. we will assist anyway we can. ( btw i am a redneck ) jmo
from that pic i can tell either you have a 4 wheel drive or a station wagon and you like frog legs. lol ( i like all )That is me.