[rotorwrench]

The GAV is a mixture trim adjustment that works with the main jet to cover all possible fuel mixture needs. It will compensate for altitude and temperature changes by manual control. Auto engines will run from between a lean condition of 16:1 to a rich condition of 12:1. They pull good power at 13:1 but get better mileage at 14.7:1 so there isn't much variance there of air to fuel mix.

Manual control of fuel mixture takes some getting used to but it generally boils down to adjusting for best engine performance any time it feels necessary to the individual operator. A person can fine tune the system while running down the road or a person can get used to where it works best for their environment and adjust to their own desired settings at any time.

I've noticed that fuel mileage can vary depending on how you set it. A car engine will run just fine on a bit leaner mixture but it may not have best performance with that setting. It will still run and work and mileage will be better. If a person sets it too lean then they may notice a back fire hickup now and then when pulling a heavy load up a hill. Personally, I set it for best running and don't worry about the mileage. I just leave it where it is unless the temperature drops. If I store the car for longer periods I shut it off and pull the choke to keep stuff from getting into the carb (no air filter). I shut off the fuel valve and run the carb dry before messing with the GAV & choke. This modern fuel is not something I like setting around for too long in confined spaces that are vented to the atmosphere.