The Ford Barn

nkaminar · 07-25-2024, 07:34 PM

The GAV stands for gas adjustment valve. Like a lot of things on the Model A the air/fuel mixture is adjustable by the driver. The knob that you pull to choke the engine also turns and adjusts the GAV. Turning counter clockwise will put more gasoline into the engine while turning it clockwise will put less gasoline in. It is usually turned one turn counter clockwise to start a cold engine and kept at about 1/4 open to run the engine. However, each car is different and a little experimenting is needed. Do not turn the GAV tight against the stop (clockwise) because it can damage the needle valve and seat.

Another way to add more fuel is to slightly pull out the choke. This is a temporary measure just used to see if running lean is the problem. Try pulling out the choke about 1/4 of the way, more or less, to see if the car is running lean. You can keep it out using one or more cloth pins or a needle nose Vice Grip pliers. If pulling out the choke works but not the GAV, then that means there is a clogged jet in the carburetor.

07-25-2024, 07:34 PM	#1
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 5,852	Re: Backfire through carb on acceleration The GAV stands for gas adjustment valve. Like a lot of things on the Model A the air/fuel mixture is adjustable by the driver. The knob that you pull to choke the engine also turns and adjusts the GAV. Turning counter clockwise will put more gasoline into the engine while turning it clockwise will put less gasoline in. It is usually turned one turn counter clockwise to start a cold engine and kept at about 1/4 open to run the engine. However, each car is different and a little experimenting is needed. Do not turn the GAV tight against the stop (clockwise) because it can damage the needle valve and seat. Another way to add more fuel is to slightly pull out the choke. This is a temporary measure just used to see if running lean is the problem. Try pulling out the choke about 1/4 of the way, more or less, to see if the car is running lean. You can keep it out using one or more cloth pins or a needle nose Vice Grip pliers. If pulling out the choke works but not the GAV, then that means there is a clogged jet in the carburetor. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.