1958 johnson 18 hp carb needle question

henry954

Cadet
Joined
Jul 14, 2013
Messages
26
Guys I just got this outboard ,my first outboard by the way. I welcome myself to the forum. Ok. high speed needle on bottom is suppose to make contact with small orifice in middle of float bowl :yes? It would make sense to me that it would otherwise what are we controlling with this jet. You wouldn't believe the bear it was to make that needle seat in that orifice in the middle of the bowl.Basically that high speed needle when installed didn't protrude into the float bowl.It just stayed in the thread. problem is shes running super rich, smoking and watnot. installed new coils, plugs ,wires,carb rebuild. ..020 on the points . she idles but it aint pretty. wont go full throttle either. I'm so close, I cant stand it.Did I just #@#@^%#@# it up. Anyway, help is much appreciated.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 1958 johnson 18 hp carb needle question

It needs to be seated, then backed out 3/4 turn, then fine tune on water.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: 1958 johnson 18 hp carb needle question

I'm wondering if you might have the needle valves reversed.

The needle valve with the long taper that ends in a sharp point if the top slow speed needle valve.

The needle valve with the shorter angled and usually blunted nose is the bottom high speed needle valve.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
 

henry954

Cadet
Joined
Jul 14, 2013
Messages
26
Re: 1958 johnson 18 hp carb needle question

thanks for the quick reply.IMG_1513 (800x600).jpg its suppose to look like this right
 

Xcusme

Commander
Joined
Apr 21, 2003
Messages
2,888
Re: 1958 johnson 18 hp carb needle question

Right....for the High speed mixture screw. That is the Lower needle adjustment.
 

henry954

Cadet
Joined
Jul 14, 2013
Messages
26
Re: 1958 johnson 18 hp carb needle question

Ok guys since this issue is out of the way going to put her back together .Let you know how it goes.
 

henry954

Cadet
Joined
Jul 14, 2013
Messages
26
Re: 1958 johnson 18 hp carb needle question

holy cow it worked. That high speed needle was my problem. shes responding much better now. time to tune. thanks guys. full throttle now.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: 1958 johnson 18 hp carb needle question

holy cow it worked. That high speed needle was my problem. shes responding much better now. time to tune. thanks guys. full throttle now.

Okay... Now we would like to know exactly what was the problem with the high speed needle.
 

henry954

Cadet
Joined
Jul 14, 2013
Messages
26
Re: 1958 johnson 18 hp carb needle question

The needle did not want to go all the way in. Only thing I could think of is the machining was of on the bowl or the needle.
 
Top