carb adjustments for a 1964 40 hp johnson

[nashwinter123]

Hi,
How many turns from all the way closed do I turn the top carb adjustment. And any other important adjustments. what is the small cylinder on the left of the car that conects to the choke. It has an electrical wire connected to it. And which asjustment is which.

 

[Joe Reeves]

Re: carb adjustments for a 1964 40 hp johnson

That small cylinder would be a solenoid (Electric Choke).

That model does not have a high speed adjustable needle valve. It has a brass jet that is located in the bottom center portion of the float chamber. The top adjustable needle valve is for the slow speed, as follows.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S 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 (sounds like a mild backfire). 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 adjustment, 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.

 

[nashwinter123]

Re: carb adjustments for a 1964 40 hp johnson

Well by the electric choke there is a disk that can be turned that on it says lean. It was responding to that. And I just relised i've been trying to adjust the motor with no battery hooked up.

 

[Joe Reeves]

Re: carb adjustments for a 1964 40 hp johnson

That is a heat activated automatic choke setup, combined with an electric choke solenoid overide. The disk you mention is to be adjusted so that when the choke is set on automatic, and the engine cold, the choke butterfly would be closed. As the engine warms up, the heat would cause the choke butterfly to open. Usually worked fine when new..... Now?

The disk has a flat coiled spring attached to it that simply rests against the choke butterfly rod prong, and of course the flat spring is effected by heat that is pulled from the exhaust manifold area via a tube that should be attached.