Poor Idle

Sounds like you may have an incorrect throttle plate assembly that is not closing properly and is allowing too much air/gas mixture into your combustion chambers, thus not allowing you engine to idle.

One way to look at your four (4) combustion chambers is just what you are experiencing:

A. An increase in flow of a gas/air mixture increases your engines rpms; and,

B. A decrease in flow of gas/air mixture decreases rpms; and,

C. "Totally" restricting the flow of gas/air mixture will make an engine stop; and,

D. Appears you are trying to achieve slow idling rpms ...... like between above paragraph B. and C. ......... however, closer to C.; hence, the throttle plate, has to restrict and allow less gas/air mixture into the combustion chambers for rpm reduction.

Works similar to driving 50 mph in (55) degree damp weather with your Model A front windshield open .......... if you want to get just a little bit warmer inside the cab, just keep closing the windshield to restrict the flow of cool air .......... totally closed, no cool air.

Keep posting what you find as you go ..... it helps immensely ...and so many on this Forum are seriously willing to assist.
 
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H.L., I do really appreciate all the help on this forum, I read almost everything that comes up, just trying to absorb what I can. With the throttle plate turned over it fits really well and I can easily turn down the idle speed, completely stop the engine now, couldn't do that before. I can turn the idle mixture screw now and it reacts enough I can find a sweet spot. Right now it's at about 1.25 turns. It is still missing and stumbling some, but after it's good and warmed up it's not too bad. I took it out and drove it 5-6 miles, 45 mph to putt-putt-ing around at 20 mph.

1.) I think I traded one carb problem (tilly) for another (ebay Zenith) I think the ebay dude put the throttle plate in upside-down.

2.) I think I ended up with the timing retarded in my attempt to get it running better, when all the time it was the upside down throttle plate.

3.) I'm also thinking the gas is questionable, I hope to get some ethanol free fuel in it soon.

I now feel I can't take anything for granted, I'm going to order the best quality points, condenser, and plugs. I also might get a new coil and figure out how to make sure the polarity is correct.

At least she's back to being a driver, here is a video of how it's currently idling. https://www.youtube.com/watch?v=e3vA0X0naMY&feature=youtu.be
 
Everyone will agree it is so rewarding to be doing all this by yourself .... nothing like hands on, learning as you go, and attempting nothing but perfection ........ old vintage Model A's can be so very dependable when properly maintained and provided with the best of parts available ...... all of the time and efforts provided on this Forum would cost a fortune if people had to pay for verbal help by the hour ...... lots of charitable people on this Forum who sincerely care for others.
 
hale1776 said:
Have you checked your throttle shaft? it goes straight through the cast iron casting and when it wears you get a vacuum leak around shaft. They make oversize ones just to solve this issue.
Google :Model A Ford Zenith Carburetor Throttle Shaft & Lever - Oversize Diameter

Make sure good gasket seal between carb and manifold as well.
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Last year I had the same problem and my throttle shaft bushings were bad, to test just hold the shaft and move back & forth you will feel slop if it is bad. I replaced and it fixed the problem
 
I'm going nuts trying to get a nice smooth, proper Model A, idle.
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FWIW, I had this problem on a Model T and it turned out to be the camshaft was worn. Put in a reground (stock grind) camshaft and problem solved.
 
BILL WILLIAMSON said:
ALWAYS RECOMEMBER, IF your GAV affects your idle, IT'S IDLING TOO FAST!!!
Bill Slow
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Words to live by!:)

Just a quick update, my idle just keeps getting better.:)
I've put about 30 miles on it since putting the Zenith on, put 6.5 gallons of non-ethanol 90 octane (only choice for non-ethanol) today, we'll see how that changes things, if any. I just have the floorboards setting in the car with one screw each since I flushed the tank. So it's noisy and hot to drive. I'm amazed how slow it will idle now, retard the spark and it sounds like a steam engine.;) Since the floor is out, I want to change the rubber between the rear mounts and frame, then new rubber in the float-a-motors! Thanks again for all the assistance!:)
 
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