Stalling at stop

[Moe]

I have set my float right on the money, to low and to high and my 31 still stalls when I come to a stop. It seems to be running rich. It sometimes back fires going down hill when I let off the gas. I have rebuilt the carb, blown out all the passages twice, but no luck. Any suggestions?

[msmaron]

Dumb...but is the GAV the choke rod OPEN TOO much.. that is a fine setting, sounds like the carb has a lot of gas and it is running very rich. Try turning it clockwise to close it and see about adjusting the throttle on the carb

[Moe]

The GAV is all the way clockwise and the choke is wide open.

[SteveM]

Could be that the GAV is not sealing well. I think there are tests in Moller's book on checking for leaks.

If you have a replaceable seat, try a new one. If not, try honing it:

You can make a hone out of a couple of GAV's:
http://model-a.org/gav_honing_tool.html

That worked for me.

Also, dumb thing to check - make sure that the compensator jet is really a compensator jet and not a GAV seat. My dad mistakenly put one in and the car ran REALLY rich.

Steve

[allen]

Im not so sure its the carb, I have guess by now you check the timing and reset the points, but if you think its carb do you have a friend who would let you try his or hers carb for a quick run about, I still going to put my money on timing if you have you setting too retar this could explain your rich running good luck keep us posted

[Michael in Sedona]

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A couple of thoughts. I've had the exact conditions that you describe, and I adjusted the float to be right on the money per Les Andrews book, but it still stalled. Turned out I had a pinhole sized leak in the float. New float, no more stalling.

On another Model A, I had the float set correctly and the GAV fully closed, and it still seemed to be running rich. I was able to fix that one temporarily by advancing the timing a little. No more stalling, but I still need to check that GAV and see if it needs some work.

[HDowse]

I had the same problem with my Zenith and finally decided to check the jet sizes per Les Andrews' book. All were too large for the specs so I soldered them up and redrilled the correct sizes. It doesn't run as rich now and the GAV can be leaned out at road speed. Just another possibility.

[Mitch//pa]

here is something to look at

http://www.model-a.org/symptoms.html

[RonC]

Check your point setting (0.020) then check your timing. With the spark level all the way up, withdraw the timing pin and turn it around. Remove the distributor body and cap. Turn on the ignition switch, put transmission in neutral and set the emergency brake. Insert the timing pin in backwards with pressure and turn the engine over with the crank. As soon as the the pin sets into the timing gear recess a spark should occur between the breaker points. If not adjust timing.

[Model A Man]

when this happen to me it ended up being a vaccumn leak. I replaced my manifold gasket and all was fine. there is a way to check this by spraying something around the manifold but I can't remember what it is that people use. also if you have a vaccumn wiper make sure it is not leaking.

[Marco Tahtaras]

When I've encountered this it's been correctable by readjusting the idle air adjustment (idle mixture) screw. If I recall correctly the direction would be closing it very slightly (richer). This may require readjusting the throttle stop screw to compensate.

I suspect the root cause is a very slight internal restriction, but this has solved the problem the couple times I've encountered it. The float level is far more forgiving than we are led to believe and must be WAY off to cause this problem.

[Chris in CT]

Moe, What makes you think you are running rich? What I'm hearing makes me think you are running lean. The backfiring on decelleration is a lean symptom, and the stalling at stop signs is also a lean symptom. Marcos suggestion to enrichen the idle mixture has merit, and has worked for many of us. Good Luck

[Aerocraft]

It has been my experience that the engine will stall at a stop when the idle mixture is too lean. That is assumming that the float level and jets are all within spec. Richen the idle and see if it helps.