"The GAV knob (gas adjusting valve), opens and closes a little valve inside the carburetor that ports fuel direct to the cap jet, bypassing the comp jet and secondary well. Its function is to richen the gas mixture. You will get better mileage the more it is closed, however, the more it is closed the leaner is the mixture and you have less power. Most cars run well with it 1\4 to 1\2 turn open. If you are climbing a steep grade and the engine starts to ping one usually retards the spark slightly and opens the GAV a little more. Anything more than a full turn open and the valve is completely open." Tom Endy

Before Driving Preliminaries

Steps To Start Your Model 'A'

    steps in starting a model a animated
    Steps in Starting a Model A.
  1. Make sure parking brake is on (pulled towards you)Note: with earlier models the parking brake is on the left hand side of the driver.
  2. Turn on gas (lever pointed down) Note: with earlier models the gas shut off may be under the hood.
  3. Retard spark lever (Lever on the left of the steering column. All the way up) Note: Always retard the spark lever when starting. Starting the vehicle with the lever advanced (down) can damage the starter if the engine kicks back.
  4. Pull throttle lever 1/3 down (Lever on the right of the steering column.) The lever also acts upon the accelerator pedal on the floor. Note: The throttle-lever starts to open the throttle at 3:00 on a clock. To start I set my lever at/or about 4:00)
  5. Turn Carburetor Adjusting Rod to the right until closed, then 1 full turn to the left to open. If the vehicle is warm turn open to the left will be fine.
  6. Put gear shifter into neutral
  7. Turn key on
  8. Pull back on the choke (Carburetor Adjusting Rod) and press on the floor starter button.
  9. After one turn, release the choke. Mine usually starts on the next turn. (Pulling on the choke enriches the piston chamber with a lot of gas at once, which helps to start the engine when it is cold. If the engine is warm, there is no need to choke. See Carburetor Basics)
Shift Pattern
Shift Pattern

As Soon As It Starts

  • Advance Spark Lever half way down the quadrant. (I set mine at about 9:00 to 8:00 on a clock)
  • Close the Carburetor Adjusting Rod to ¼ turn open.
  • A gentleman told me once if your engine is timed correctly,for every 5 MPH increase in speed, you would move your Spark Advance Lever down one notch. In general, for normal driving, it is ½ to ¾ of the way down. Lower it further for high speeds.
  • When the engine is under load such as climbing a steep hill, retard (move up) the Spark Advance Lever.

Driving and Shifting the Model A

    double clutching
    Driving and Shifting.
  1. The Model A has just been started.
  2. Apply the foot brake.
  3. Release the parking brake.
  4. Disengage the clutch (push down)
  5. Move the shift lever to the left and back for first gear.
  6. Let up on brake
  7. Gradually release clutch and lightly accelerate at the same time.
  8. When the car has reached a speed of approximately 10 MPH, push in the clutch, shift into neutral, let the clutch out, put clutch back in, shift to 2nd, let clutch out. (takes about "one-one-thousand, two-one-thousand, three-one-thousand", not rushing the count.)
  9. When the car has reached a speed of approximately 20 MPH, push in the clutch, shift into neutral, let the clutch out, put clutch back in, shift to 3RD, let clutch out.


  • As you get to know your Model ‘A’, the above speeds for shifting may vary
  • For economical driving, reduce the quantity of gasoline in the mixture by turning the GAV adjusting rod to the right as far as possible without effecting the operation of the engine. This will increase gas mileage.
  • Turning the GAV to far to the left results in a “rich mixture”. Such a mixture has too much gasoline and should be used for starting and warming up only. Running too rich a mixture causes excessive carbon and overheating. In addition it wastes fuel. (For normal driving, the GAV is 1/4 turn open)
  • double clutching
    How to Double Clutching a Model A.

    Double Clutch to Down Shifting

  • To down shift from third to second: Disengage (push in) the clutch, shift to neutral, reengage (let up) the clutch and rev the engine; then disengage the clutch again and shift to second, after which reengage the clutch. Basically: "clutch-neutral-clutch-rev-clutch-shift"... fairly quick.

  • Paul Modlin