GAV lever

[MickyD]

I need to ,earn more about my Model A. Should you close the GAV when you turn off your engine? If you leave it in an open position will the GAV cause fuel to leak?

[40 Deluxe]

Originally Posted by MickyD

I need to ,earn more about my Model A. Should you close the GAV when you turn off your engine? If you leave it in an open position will the GAV cause fuel to leak?

No. It is an internal mixture adjustment that is effective only when the engine is running. It controls the air/fuel ratio. The driver opens the valve more when the engine is cold and can adjust for specific operating conditions.

[J Franklin]

The GAV doesn't contribute to leaks unless not installed properly or damaged. If anything open it a turn and your all ready for the next cold start.

[MickyD]

Thank you all. I know how to adjust it when I start my car but was unsure about the rest.

[nkaminar]

Micky D, If you do close the GAV, just remember to not turn it in too hard, just enough to close it. Otherwise you can damage the seat.

[rotorwrench]

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The model A was made with a lot of manual controls available to the operator. Later cars went on to more automatic type controls as time went by. Few people in the modern era would know how to adjust all those manual controls.

I pull the choke to get a richer starting fuel charge when the engine is cold. During warm up, I slowly decrease choke opening till the car is warm enough to operate without it. While running down the road, I only adjust the high speed jet or GAV to get best performance under the current conditions and then leave it there. I would shut the fuel valve off when putting the car away but seldom messed with the GAV or idle metering unless the engine performance was indicating that a change was needed. All of this has to be taken into the context that the car is equipped with a Tillotson carburetor and not an original Zenith.

The above statement may be contrary to what some instructions tell you but keep in mind that fuel quality varied a lot back in the model A era so this allowed an operator to get best performance on the fly. Few automobiles were equipped with a cabin adjustable main fuel metering system after the model A & B era. Most were fixed by the use of non adjustable main metering jets. Carburetors evolved quite a bit in just the four years following the end of model A production.

[Bob Bidonde]

When you turn-off your engine, leave the GAV in its run position. If parking your "A" overnight, run the engine with the gas shutoff closed to empty the carburetor.

[MickyD]

I have not tried running the engine with the gas shut off valve closed to empty the carburetor. In my mind I thought of it, but I also thought it may take too long to refill, the carburetor. I will try that tomorrow.

[J Franklin]

Originally Posted by MickyD

I have not tried running the engine with the gas shut off valve closed to empty the carburetor. In my mind I thought of it, but I also thought it may take too long to refill, the carburetor. I will try that tomorrow.

If it takes too long to refill there is something wrong.

[shew01]

Originally Posted by MickyD

I have not tried running the engine with the gas shut off valve closed to empty the carburetor. In my mind I thought of it, but I also thought it may take too long to refill, the carburetor. I will try that tomorrow.

On my Zenith carburetor, turning on the fuel valve refills the carb enough to start easily in a couple of seconds (after running the carb dry with the fuel shutoff).


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[Bruce of MN]

Originally Posted by shew01

On my Zenith carburetor, turning on the fuel valve refills the carb enough to start easily in a couple of seconds (after running the carb dry with the fuel shutoff).


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Same here.

[MickyD]

It started right up like it is suppose too and idles fine.. Just bad day. See my post Bad day, gas leak. It will get better.

[mass A man]

What are the benefits of running the carb "dry" if just parking overnight? Or even for weeks. I've never had a problem starting any Model A after sitting a month (read last summer, no car shows).

[shew01]

Originally Posted by mass A man

What are the benefits of running the carb "dry" if just parking overnight? Or even for weeks. I've never had a problem starting any Model A after sitting a month (read last summer, no car shows).

The idea is to get as much gas out of the carburetor as possible at shutdown so that a pool of gas will not have the opportunity to gel up inside the carburetor and cause issues. I have a LOT of problems with our lawn mower gelling up on ethanol gas. So, I run non-ethanol gas in my Model A (and lawn mower) whenever possible. Still, I like to run the carburetor dry when I come home from a trip. It’s a free simple task, and it only takes about a half second to turn off the valve (which is inside the car) for me about a block from my house. The car normally runs out of gas just as I reach the top of my driveway, and I coast into the garage. For me, it’s just preventative maintenance.


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[mass A man]

Yes, a lot of us have had problems with the modern gas. I run the A on local regular gas, knock on wood, no problems since all non-metal parts that gas may contact with on my Model A has been "Ethanol-proofed" (Tank float, gas cap gasket, gauge gasket, a steel needle valve and carb gaskets). I figure by leaving the float bowl "full" it creates less air in there to form any skin/scum or gel since the bowl will not be completely "dry" at all. Sort of the same thought of filling the gas tank up for the winter to prevent rust from any condensation on the tank walls.