Car stalling at sudden stops.

[2rosella]

..........

[Tony Hillyard]

I would suggest it's not the float that needs adjusting. Double check you have the choke/mixture control adjusted correctly after the engine is warm. I would be very surprised if the car runs well normally then stalls when it is subjected to a sudden stop, the problem is the float adjustment.

[johnbuckley]

I agree with Tony #2, it's often a sign of a slightly weak mixture. (Obviously check ign circuit is OK etc etc).. and the braking sloshes the fuel level slightly making it even weaker with the G force ( yes even with A brakes!). I f everything else running well other than cutting out with sudden stops.( and it's not an uncommon problem with As and many cope with judicious use of the hand throttle when approaching traffic lights) ..before taking carb to pieces try just enriching the idle mix a smidgin. Internally the carb there could be an leak where idle jet threads into upper body Apart from carb making it weak another possibility is slight air leak at manifold.

[Mitch//pa]

I have found that it's usually the float is set to high on this chart that is the most common cause. Brattons sells different thickness float valve gaskets. An intake gasket leak, or a lean condition will cause other driveability symptoms as well. An inline spark tester or a meter / testlight installed to the coil will show if you have an intermittent with the ignition circuit
A good carb site
http://www.modela.org/symptoms.html

[coupe1942]

This may sound odd, but my '30 tudor used to stop every time I drove a few hundred yards and came to a stop sign out in my street near work. It would then crank right back up, but it did this several times one week.

The culprit was that I had put too much junk onto my key chain and there was a slight speed bump near that stop sign. Each time I crossed over it the weight of those dangling keys would shift and then actually turn the ignition switch off as they slid from side to side. Took em a few times to figure it out. Felt foolish at the time, but at least it was an easy fix to remove the dangling junk from my key chain.

[Tony Hillyard]

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I bet that was a real brain teaser Coupe 1942!!!!

[Al 29Tudor]

Like Mitch said --- it is very likely the float is set too high. I've been able to add a gasket on two different cars to lower the float to fix this problem.
Al

[johnbuckley]

ah well, there we go Fordbarners.... some reckon the mix is too weak..... others that it's rich !

[Jacksonlll]

I find many times it's an intake leak. Remove carb, file flat the mating surfaces where they attach to each other. Use a file and a mirror to do the manifold. When you get these two surfaces cleaned up, use a new gasket. If this is not the leak, it may be in the manifold or your gasket. Very hard to find, but this little leanness can cause your problem.

[Terry, NJ]

Get a "B" carburetor! The float is going north-south when the car is going east-west, Crosswise to the car's direction. Plus it handles more air.
Terry

[jwilliams81]

From everything I have been reading, it seems the float would be the problem.

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

"If the fuel level is set to 1/2" (from the gasket surface of the bottom casting, with the engine not running) it can allow some carburetors to stall when the vehicle comes to a quick stop. If the fuel level is less than 1/2" (from the gasket surface of the bottom casting, with the engine not running) it can allow some carburetors to drip gasoline from the air intake. If the fuel level is set greater than 11/16" (from the gasket surface of the bottom casting, with the engine not running) it can allow some carburetors to run lean mixture, with rapid acceleration."

[Fred K-OR]

Originally Posted by Terry, NJ

Get a "B" carburetor! The float is going north-south when the car is going east-west, Crosswise to the car's direction. Plus it handles more air.
Terry

And uses more gas?????

[Chuck Sea/Tac]

Originally Posted by coupe1942

This may sound odd, but my '30 tudor used to stop every time I drove a few hundred yards and came to a stop sign out in my street near work. It would then crank right back up, but it did this several times one week.

The culprit was that I had put too much junk onto my key chain and there was a slight speed bump near that stop sign. Each time I crossed over it the weight of those dangling keys would shift and then actually turn the ignition switch off as they slid from side to side. Took em a few times to figure it out. Felt foolish at the time, but at least it was an easy fix to remove the dangling junk from my key chain.

Mid 50's gus wilson's model garage, in popular science magazine.

[Tom Wesenberg]

Originally Posted by Chuck Sea/Tac

Mid 50's gus wilson's model garage, in popular science magazine.

That's from the days when Popular Science and Popular Mechanics were still good magazines.

[Al 29Tudor]

Thanks for updating us on your successful adjustment.
Happy motoring.
Al

[wmws]

Can anyone explain why lowering the fuel level in the carb would cure the sudden stop stalling problem. My car stalls sometimes when the engine is cold. That would indicate to me that it is too lean. When the engine warms up it is fine. Also when you hit the brakes the gas would tend to move away from the throat and jets making the mixture leaner. So wouldn't lowering the fuel level make the problem worse. I must be missing something.

[jwilliams81]

Originally Posted by 2rosella

Hello All,
My problem is now fixed. I made a gauge to measure the fuel level in the carburettor and it was just under 1/2". It should be around 9/16" to 5/8", so I set the level at 5/8" and the motor idles nicely and it does not stall at sudden stops anymore.
So basically it was the float and needle & seat which needed adjusting.

That's awesome that fixed the problem. Did you add shims or a thicker gasket to the float valve? Or did you bend the float some how?

[H. L. Chauvin]

There are many reasons why 86 year old worn, Model A Zenith carburetors malfunction at sudden stops, but here is just one (1) minor correction that helps:

1. The round bottom shape of both the Zenith bowl & Zenith float has lots to do with this Model A engine stalling condition at abrupt stops.

2. The aftermarket Marvel carburetor with the "non-round bottom" and the Ford's later "improved" design of the Model B "transverse" round float solved this problem; however,

3. After hearing this same Model A engine dying complaint at abrupt stops thousands of times, Mr. Rex Reheis addressed this original Model A Zenith carburetor problem in the book written by Mr. Gordon Bigger.

4. With the carburetor installed on the intake, (while using the improved Dave Renner gauge, accurate within .010", as opposed to the fly-by-night gauge sold in Model A catalogs), he recommends very accurately adjusting the float valve with washers such that the washers allow the float gauge to lower the Model A Zenith's bowl fuel level 5/16".

5. Ford recommended 5/8" from the carburetor's horizontal meeting flange to the top of the fuel in the bowl ...... Mr. Reheis recommends this to be 15/16".

6. One will never experience adjustment differences after experienced Model A recommendations are made ............ unless one tries them ...... as far as advice ...... cigarette manufacturers are still cashing in on future lung transplant victims.

[jwilliams81]

Originally Posted by 2rosella

I had a few different thickness shims and it was a bit of a task getting the correct ones in. I think the carburettor came off and on about 6 to 8 times to get the fuel level at 5/8".
And NO, I did not attempt to bend the float as I heard you can damage it trying to do so.
In my opinion the shims (Fibre washers) did the trick.

Perfect. Did you get the shims at a local auto parts store or order them?