Governor adjustment

I now have the governor adjusted the problem I'm having now is when I get it to high idle sometimes it will cough and act as if it's running out of gas, I can open the choke part way and it will stop and I can close the choke, also I have to hold the throttle open are it will close on it's own, the book says tighten the nut on the shaft but there is no nut to tighten.
 
The cough and hesitation is likely too lean. It can also be caused from retarded timing, stuck distributor weights, or points out of adjustment.

To adjust the mixture, get it warmed up, adjust the idle mix first (the small screw on the side of the flange where the carb bolts to the intake). I believe that one adjusts backward, out is lean, in is rich. Lean it until it roughs up, then rich to best idle, then about 1/8 turn in more.

If the main is adjustable, bring the engine down to slow idle, then suddenly goose the throttle to full speed. It should accelerate without hesitation or coughing. Turn the main adjust (the larger screw) out to richen it. Try about 1/2 turn at a time, repeating the acceleration test until it takes throttle. A single puff of black smoke is desirable.

As for the throttle friction, not familiar with that specifically, but somewhere there should be a spring loaded friction clutch to hold the throttle lever in place. Some have a compensator spring also, but again, not sure on that model.
 
The screw/jet your talking about you can run it all the way in and it does nothing, it's a zenith carb If that helps any?
 
If adjusting makes no difference: I would have to guess it needs a good thorough cleaning. Acts like there is a blockage preventing fuel from going through the ports.
 
If you only have one adjusting screw, that will most likely be idle mixture. Will have no effect above 500 to 750 rpm. That leaves the high speed and power on a "fixed jet". Any restrictions in those passages will have the symptoms you describe. Pull it apart and clean all ports and passages.
 
If the idle mix adjust screw does nothing, good indication the idle circuit is not delivering fuel, which would cause it to be lean.

I'm sending a cut-away view of a typical updraft to help you find your way around.

A couple of things to check:

Open the carb back up, looking at the diagram, follow the idle circuit from the main well up to the upper housing. Notice the fuel must be drawn up through the small hole beside the venturi. Be sure the hole in the gasket is aligned with the holes in the casting, and the gasket is compressed between the 2 surfaces when the screws are tightened. Sometimes the top is warped in that area, and will need to be filed flat in order to seal.

Also look at the fit of the throttle plate. With the idle stop backed off, the plate should be centered in the housing bore. If not, carefully loosen the screws and center the plate. Note the 2 tiny holes in the side of the bore. That is the idle and mid range fuel ports. The throttle plate needs to be between the holes when closed.

Continue studying the idle circuit in the drawing. Be sure everything is clear and in place. This is a generic drawing, may be some differences, but the theory is the same.
Updraft Fuel Circuit
 
On your throttle, there should be a balancing spring back at the mid way point of all the linkages that helps keep it at full throttle. The discs are probably worn on the friction mechanism and no nut to adjust tension. Can jerry rig extra tension if necessary but spring should take care of it.

On the Zenith carburetor you will not have a main adjusting screw. It might have a electric shut off or not depending on who has been working on it. That engine has a pretty cold manifold so it will have to be warmed up good to get a good smooth acceleration from low idle to high speed. The idle mixture adjustment has to be made at a very low engine speed or it will have no effect in or out on idle smoothness. It can slightly effect acceleration if set too lean even at idle though. Make sure timing is set to correct degree of advance at full throttle. Don't know for sure what it is but it will be in the neighborhood of 20 degrees before top dead center at full throttle.
 
The governor has started to surge again from time to time, I can get a hold of it and it will stop. It doesn't have a thermostat in it so it takes forever to warm up,on high idle I can get it up to about 2K rpms and timing sets at 2420 rpms at 17?Btdc.
 

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