GAV use

[German guy]

My GAV was frozen in the full open position when I bought the car. Being new to the Model A I did not know that it was even supposed to turn, and used it as a choke only. After seeing videos about it I did a thorough cleaning of the carb linkages and freed it up.



Since that time I have played with it a lot and have never found any setting that gives me better, smoother running than fully closed. Even cold starts in cold weather two pulls on the choke with GAV fully closed is enough to get it running smoothly. Am I doing something wrong?

 

[Bruce of MN]

Since there isn't an accelerator pump, pulling twice has no effect. Crank the engine with the choke pulled to draw extra gas in and push it in when the engine starts or sooner, to keep from flooding.

 

[Jim/GA]

My GAV was frozen in the full open position when I bought the car. Being new to the Model A I did not know that it was even supposed to turn, and used it as a choke only. After seeing videos about it I did a thorough cleaning of the carb linkages and freed it up.



Since that time I have played with it a lot and have never found any setting that gives me better, smoother running than fully closed. Even cold starts in cold weather two pulls on the choke with GAV fully closed is enough to get it running smoothly. Am I doing something wrong?

This is very common. One or more of your jets has an orifice diameter that is too large, so you do not need to enrichen the mixture with the GAV for cold starting and running.

I recently found on a friend's Zenith carburetor that he was missing the little jet that gets installed down in the GAV housing hole. So his GAV was always making the mixture very rich, even when screwed in all the way. We added the missing jet and the carburetor functioned normally, as expected.

So look down in that hole to confirm you have this jet IF YOUR CARB IS SUPPOSED TO HAVE ONE. They were only used in the early years of the Zenith carb, and then they were eliminated. When you look down in that hole, see if it looks like you have threads at the bottom for a jet. The later carbs had a tapered base machined in the bottom of the hole for the GAV needle to seat down into. If you have that, then no jet is used.

 

[Bob Bidonde]

This slide may be of help regarding using the GAV.