Car stalls at idle

[sphanna]

Yesterday during an 80 mile run, my engine would not idle. Ran great day before. Quits at all stop signs unless I increase idle speed with throttle lever to fast idle. Also during coasting from highway speed to under about 20 mph in gear, it intermitenly "after fires" with a bang in the exhaust. NOT a BACKFIRE through the Carb. but in exhaust. Any help as what would cause this. Car has always ran a bit rich and still does it seems. Unless it is too lean at Idle now. Don't think so. Bad condenser??? Leaking exhaust vlv??? Maybe worn dist. drive gear??? Replaced with rebuilt Carb and Distributor about 800 miles ago. Also at that time installed new modern points. Ran great until yesterday. Car has never really idled as smooth as some but now just before it stalls, it runs very rough as it quits.

[Blessyouboys]

If the car were mine, I'd start by checking the float level and idle mixture.

[Aerocraft]

Since it ran well the day before, I suggest that you remove the carb, separate the halves, and blow all of the passages out. Remove the idle jet and make sure it is open and not plugged. Reassemble and run. Gar Williams

[Purdy Swoft]

All good info. after cleaning be sure to check manifold and carb flange for warpage and failing gaskets. Two main causes of stalling at stops are , you need to slightly lower the float and vacume leaks anywhere it can leak from wiper motor to the carb and manifold.

[sphanna]

Thanks to all who responded to my question. Great help. Fixed the stalling problem

Steve Hanna

[sphanna]

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I am new here. WHat is the difference between Senior member, Member, and Junior Member. I signed up today and this is a mystry to me

[Gary WA]

Has to do with the number of posts! nothing to be concerned about!

[Model A Man]

could be a vacuum leak

[Patrick L.]

OK, good post,,, but,,, what fixed the problem ??!!

[sphanna]

I found that my points had gap reduced. Also I did find that it idled smoother to open the GAV about 1/2 turn. This was a surprise to me as I always thought it was running to rich. Always had an exhaust smell that smelled rich.

[Chris in CT]

Hi sphanna, It is possible for your main and CAP carburetor circuits to run too rich, and for your idle circuit to run too lean. Try closing that GAV a little, and turning the idle mixture screw IN until the engine slows down, and then back it out until the engine picks up again. Good Luck!

[steve s]

Originally Posted by sphanna

I found that my points had gap reduced. Also I did find that it idled smoother to open the GAV about 1/2 turn. This was a surprise to me as I always thought it was running to rich. Always had an exhaust smell that smelled rich.

The paradox of backfiring is that accumulation/explosion of too-much unburned gas in the exhaust system is due to too-little gas getting into the combustion chamber. The air/fuel mixture is then too lean to ignite and gets swept on out in the exhaust, where it can accumulate and light-off every once in a while. Although the most obvious culprits would be too-low float or plugged carb jets, most of the time it's due to electrical problems, like closing-up points failing to provide enough spark.

Steve