A Model A mystery

[700rpm]

I have had my 1929 Tudor since 1961. I refurbished (can't call it a restoration) it in 1980, at which time I had the engine rebuilt by a reputable local.

However, since the very beginning, 1961, this car has stalled and died when I come to a stop unless I work the hand throttle. It has done this through new points, condensers, coils, and numerous carburetors, even a different engine. My 30 PU does not do this. Other Model A's I have owned have not done this. And I haven't solved this even after 49 years of driving this car!

I have traded carbs with the pickup and it still does it.

I obviously need some help here. What might cause this, other than the things I have already tried?

[Dave in Boise]

Hmm.. I'm kind of new to this as compared to the history of this car, but here are some ideas:
1) sit at idle and mash the brakes down.. Does the engine falter or stutter at all at full lopey retarded idle? I have seen this where there was a short in the brake switch, essentially grounding out the systemenough to kill the engine.
2) Usally Zenith float leveld so this.. How about running the engine at a full gallop, while still stationary and then pull your foot off the gas completely, as you would when stopping. Maybe the distributor has enough lash that on deceleration it moves too far retatrded or the idle is set too low..
Hope this helps!

- Dave in Boise

[Dave in MN]

I know you stated the problem was present even with a different engine so this may be a long shot... Is it possible you have an intake leak that causes a lean condition when warm. Try this: With the engine up to operating temp and at idle, spray some WD-40 at the connection of the intake manifold to the block. If the engine stumbles or speeds up it would indicate a leak, that may be your problem. Just had a car in the shop that had the same symptom and solution. Good luck...
Dave in MN

[ChicagoBob]

Does sound like a vacuum leak. Lot's of places to look, especially the wiper lines, if you have a vacuum wiper.

[Jack '29 Sport Coupe]

I had that problem-----until I adjusted the "idle stop" so that no matter whether or not the throttle was "cracked" or jammed all the way to the up position. Problem solved----and the idle is just fine. No doubt you've done this, but you didn't say, lol.

Jack

[700rpm]

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Thanks everyone. I'll try those things. A vacuum leak is a good possibility.

Jack, I don't understand what you did. Could you explain that a little more?

[29RPU]

Do check the brake switch idea. I have heard that several times now.

My thoughts: If the condition has continued thru an engine replacement, then it must be either a short in the braking system, or a part that has been present on both engines. In other words, did you use the same distributor in both engines? How about adjustment of the mixture? I know that all As have their own resipe for running good...maybe it is running too lean or too rich. Lasty, I have a friend who's A would cut out sometimes. It turned out that he had some debris in the gas tank that would come to rest over the outlet and hinder the gas flow.

[Patrick L.]

I think Jack was the fella that was using the hand throttle to control engine idle speed and was having engine stalling issues.. It was suggested he set the idle speed with the carburetor idle stop screw and re-adjust the idle mixture..That is, if memory serves..

[1928Pickuppain]

Check your exause manifold pipe Alot of times new engen dosent meen new manifold or exaust pipe. I once had a honda 3 whealer that did this. It sat in a barn for 20 years and when i pulled it out this is exactley what it did; start fine then ater it got warm if you stoped it would die. turns out i had a slight maby half blockage in my exaust manifold / pipe. while driving there was enough pressure to keep the air forcing out the of the pipe but when at a stop there wasn't enough pressure and the insuing back preshure from the clog would stall out the engen the reason it starting fine when cold is, as the engen warms up the heat causes the air to not flow as good as cool air. I also just had this same problem with my buddys 65 mustang mouse in the muffiler cut it off and it ran great. (little lowd though)

[Rainmaker Ron]

Few problems could follow you that many years through that many changes to the system. I have had some mighty strange things happen with Model A’s and I love a puzzle. My favorite thing when we were in the parts business was to have a customer call me and describe symptoms and have me tell him what was wrong. Logic leaves me with few guesses in your case but I can think of one off hand.

Lets say you crank up the old flivver and set off for a ride. Every thing is normal, car is running fine, generator is genning, electrical system is seeing something around 6 volts. Now we come to a stop sign and as we slow down the generator output falls below 6 volts BUT the old cutout doesn’t open and the system voltage drops way down while trying to motorize the generator. By this time the car has died and the cutout opened just at the last moment. You didn’t say, but maybe you sometimes need to “rap” on the cutout to unstick it. Could happen!

Disconnect the generator, ground it out and take a spin. It won’t be much trouble to try it.

Ground circuits are another thing that cause strange happenings. Add a ground direct from the battery to the transmission.

Rainmaker Ron

[John Butts in CT]

Ron, I like it! Never hurts to clean all electrical connections ("bright and tight"), and a second ground cable is a MUST on an 80 year old frame. I once had sporadic missfires on acceleration... turns out that my coil to distributor wire was JUST corroded and loose enough at the coil to be sensitive to slight changes in vibration between upshifts. Another time, my keychain was unbalanced enough to turn off the ignition. Now my start-up ritual includes making sure that the keychain leans to the right.

[Model A Man]

I had that problem and on my car it was a vacuum leak. The car had a bad manifold gasket

[Jack '29 Sport Coupe]

The adjustment I was referring to is the "throttle stop screw"
on the carburetor. Patrick, I was not referring to the mixture screw------that is
a different adjustment.

Jack

[Patrick L.]

Yes Jack,, I think I was the one that suggested you do what you did.. You're right , they are 2 different adjustments, but, they go hand in hand..

[Rainmaker Ron]

Originally Posted by John Butts in CT

Ron, I like it! Never hurts to clean all electrical connections ("bright and tight"), and a second ground cable is a MUST on an 80 year old frame. I once had sporadic missfires on acceleration... turns out that my coil to distributor wire was JUST corroded and loose enough at the coil to be sensitive to slight changes in vibration between upshifts. Another time, my keychain was unbalanced enough to turn off the ignition. Now my start-up ritual includes making sure that the keychain leans to the right.

Yep, I've seen the key chain thing and once found a coil that had one wire end already left in the post. One of the guys had the loose switch/ key chain thing and every time the car stalled he "fiddled" with the sediment bowl and off we would go again...for awhile! He could have gotten the same results by changing the condenser.

Ron

[Frank Nemo]

I to have had the key chain problem. It has become of my pre-flight check list. Key chain hanging to the right of the ignition key.