Idle air mix adjustment problem

A-Jay

A-Jay

Senior Member
I just replaced the zenith 1 with a new, not rebuilt carb. My problem is the air mix adjustment knob. It is hard to turn in or out. I can pull out the choke fine, I have checked the linkage a few times all seems as before the replacement. Any Ideas ? Can I lube anything down there if so with what ??
 
I would disconnect the choke rod from the carb. Then see if you can turn the gav. adjuster with your fingers. If you can, then you might be binding on the fire wall gromment if one is there. If not, then I would talk to who you bought the carb from. It should be a firm turn, but not so much you can't turn it with just your fingers.
 
I have experienced that problem with repop GAV needles and the housings. It was easy to fix by polishing the needle where it is gripped by the spring on the housing. Might also correct it by honing the inside of the housing.
 
Like MAG, I've encountered binding problems with repro GAV needles, housings AND drivers. For what it's worth, here's my solution.

First, remove and disassemble the driver, housing and needle. Polish and/or hone the needle and housing until you have smooth rotation. Then check to be sure that the GAV driver fits on smoothly and does not impair the rotation. I had one needle with the "half round" section just fat and distorted enough to bind and impair rotation only when the driver was pushed all the way in. It's simple to file the brass to conform to and rotate smoothly both the driver and the housing. (Not much you can do about the half-round part of the driver.)

All three parts should spin and telescope smoothly. You'll know when you're there.

Before you reassemble, be sure that the needle end is smoothly honed and that it seats properly in the carb.

Next, be sure that your choke rod is itself not binding at the firewall bracket or the gas tank support. The fit between the rod itself and the GAV driver, with its spring and sleeve, is very forgiving; just be sure that the interlock between the rod and driver is not too tight. File the driver, if necessary.

Lastly, I slide a piece of plastic shrink-wrap tubing over this connection (under the metal sleeve) to keep the rod/driver connection snug but not rigid, and I have no free play as I turn my GAV knob in either direction.
 
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I'm sure this is going to sound weird.....but I put a little
MM oil on my fingertip and slathered it on the needle. Before
you laugh at me------it turns like butter.
 
I think you mean the GAV, not the idle air adjustment. The idle air adjsutment is on the front of the carb throat. Turning it CCW increases the amount of air that bypass the throttle plate and leans the idle mixture.
 
It is not uncommon for the needle housing on unrebuilt carburetors to be slightly bent which will cause a bind when trying to open or close the needle.

The air adjustment needle is on the upper housing of the carb.
 
Temporarily remove the choke lever and turn the adjusting knob. Sometimes the little nub on the choke lever binds in the groove of the choke driver and needs to be dressed with a small file. Also Les Andrews recommends removing the spring clip on the end of the needle housing which might be pinching the needle too tightly.
 
Thanks guys, yes I did mean the GAV, sorry for the confusion. I quess thats why we're newbies. A-Jay
 
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