Stop Stall

ampico-kid said:
This all leads me to suspect a leak on the intake manifold which I just checked with starting fluid. I idled the engine down as slow as I could without stalling, and sprayed the starting fluid around the intake to block connections. Spraying around the front port had no effect, but spraying the rear seemed to make the engine run smoother for about 20 to 30 seconds. I repeated it several times to be sure, and the results were consistent. So....I assume that what I've discovered is an air leak on the intake manifold.....hopefully just the gasket. Would you all agree?

Thanks for all of the input and advice.
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As larrys40 said in post #17: "You do have to remove and get your manifold surfaced and install a new copper or steel clad gasket."
 
Ampico, the exhaust manifolds on the A are notorious for sagging at number 4 cyl. I replaced the exhaust last year on our coupe. It was sagged badly at the rear and for some reason, even at the front #1???? I took the intake and new exhaust to an auto machine shop and they shaved everything smooth. We've driven 8500 miles since installing it. I tightened it to 25 foot pounds and I check it every 500 -1000 miles.

There are lots of different recommendations on how tight to go with the manifolds. 25 #s is working for me. If I replace the gasket with the copper I may get a surprise. We'll see.

Good luck.
 
I adjusted the float level back and forth until I was blue in the face.
The cause of my problem was those two jets were not the same
height and caused it to stall. Tom Endy has mentioned about repo
throttle disks not being made right and causing this as well.
 
OK...I have a new situation to report. I swapped the good working carburetor from my Coupe (it was also a "New" Zenith-1 that I purchased about 10 years ago) and there's no more stop/stall with the Sedan and it seems to run better as well. OK I thought I'd try adjusting the float level in the "New"carb I just had on the the Sedan. Well surprise surprise.....there's no way I can see to adjust it without bending the heck out of the float. If I needed to decrease the amount of gas in the bowl it would be easy to do just by adding shims under the inlet valve, but you can't recess the valve any further into the upper carb body because there is only one fiber washer used as a seal under it. So the question is....how do you adjust the float to allow more gas into the bowl?
 
Bob, In the sketch you showed, the float would cut off gas flow when the fuel moved to the forward end of the float bowl. It would not allow an inrush of fuel as you describe. Or am I missing something?

Ampico-kid, Are the float valves different between the new carburetor and the good carburetor so that the new one protrudes further? Can you cut a really thin gasket for under the new float valve, maybe out of a thin sheet of Teflon? Is the float different between the two carburetors or are the threaded holes for the float valve different?
 
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nkaminar said:
Bob, In the sketch you showed, the float would cut off gas flow when the fuel moved to the forward end of the float bowl. It would not allow an inrush of fuel as you describe. Or am I missing something?

Ampico-kid, Are the float valves different between the new carburetor and the good carburetor so that the new one protrudes further? Can you cut a really thin gasket for under the new float valve, maybe out of a thin sheet of Teflon? Is the float different between the two carburetors or are the threaded holes for the float valve different?
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I don't know if the float valves are different between the new carb and the good one. I would very much doubt it since the float assembly on the new carb is the same as the old original. For that matter everything on the new carb looks exactly like an original Zenith.

I'm thinking about putting this "new" carb on my Coupe and see what it does there. If I get the same symptoms, I'll know for sure it's the carb.
 
ampico-kid said:
OK...I have a new situation to report. I swapped the good working carburetor from my Coupe (it was also a "New" Zenith-1 that I purchased about 10 years ago) and there's no more stop/stall with the Sedan and it seems to run better as well. OK I thought I'd try adjusting the float level in the "New"carb I just had on the the Sedan. Well surprise surprise.....there's no way I can see to adjust it without bending the heck out of the float. If I needed to decrease the amount of gas in the bowl it would be easy to do just by adding shims under the inlet valve, but you can't recess the valve any further into the upper carb body because there is only one fiber washer used as a seal under it. So the question is....how do you adjust the float to allow more gas into the bowl?
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you could try the thinnest gasket on the valve. i really don't think bending the float is a good idea.
there is a thin one in the valve adjustment kit. i haven't had that issue
 
ampico-kid said:
I guess the question I have here is this....is the car stalling because it's being starved for gas or because it's getting too much and flooding out?
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i don't believe it is getting too much gas, i say its starving. from the inertia of the fuel pulling away from the compensator jet. usually if you open up your GAV before you get to the stop sign it won't stall, from Experiences i have had, which means its starving not flooding.

i have often thought that maybe a smaller compensator jet would slow the flow of gas out of the well area and into the bowl but i have never tried that.,
 
Hello , I had that problem on my Model A also , finally found the problem was the passages were blocked in the drilled carburetor cast iron .Pulled the gas plugs out and carefully ran small drill through to clear them out, lot of rust came out, reassembled and set float , problem solved.
 
Hi gang....this story gets more confusing every day. Today's head scratcher is this. I took my known good carb (from my Coupe) and put it on the Town Sedan and I had no more Stop/Stall issues. The car also seemed to run a little bit better. Ah-ha I figured the new carb is definitely bad. Just for the heck of it I decided to put the "new" now presumably bad carb that's been giving me all of these headaches on my Coupe to see if I get the same Stop/Stall issues. I installed the new carb on my Coupe and it ran fine....no issues with the Stop/Stall and the engine ran great as it always had with it's own carb. So...that means that the new carb is not at fault. What is? I have just pulled the manifold off the Town Sedan and it all looks pretty good to me. I don't see any evidence of gasket failure, and I don't see any cracks or irregularities on the intake manifold itself. I also tested the vacuum line running to the wiper and it checked fine.

I'm going to have the manifold machined for a nice clean flat surface, get a new copper gasket, some High Temp. Caulk, and reassemble. Not sure what else I can check? Any ideas? As always...thanks for the input. Bob
 
Bob
If your manifold is machined flat you shouldn’t need any of the sealant, I don’t like them anyway on exhaust manifolds. A short term bandaid at best. Sometimes it’s a culmination of a number of things that cause these issues. Keep your steps straight of what you have done so you can return to a specific point if desired.
I would make sure you don’t have more than one gasket underneath the main jet adjust float levels to 5/8 ish . Make sure all intake and carb surfaces are tight. Keep at it. It can be frustrating even to those of us who are use to dealing with these all the time.

Make sure you don’t have internal leaks as well. Is carb throat bottom wet or dry?
If wet you are topping the jets or have a leak at the jet. I’ve also had internal cracks (rare).
Keep at it
Larry
 
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larrys40 said:
Bob
If your manifold is machined flat you shouldn’t need any of the sealant, I don’t like them anyway on exhaust manifolds. A short term bandaid at best. Sometimes it’s a culmination of a number of things that cause these issues. Keep your steps straight of what you have done so you can return to a specific point if desired.
I would make sure you don’t have more than one gasket underneath the main jet adjust float levels to 5/8 ish . Make sure all intake and carb surfaces are tight. Keep at it. It can be frustrating even to those of us who are use to dealing with these all the time.

Make sure you don’t have internal leaks as well. Is carb throat bottom wet or dry?
If wet you are topping the jets or have a leak at the jet. I’ve also had internal cracks (rate).
Keep at it
Larry
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Hi Larry and thanks for your in-depth reply. The carburetor that I'm using on the car presently is off of my Coupe and runs great on the Coupe. So it should not have any issues of any kind on the Sedan. I feel confident that I can remove the carburetor from the equation. I'm hoping that by going through all of these obstacles one at a time I can eventually work my way through whatever issues there are. I'll forget about the high temp sealant. It may take several days to get the car back together. I appreciate the guidance.
 
Hello again, if still have problems, run a compression check, hopefully what you may have is a vacuum leak on intake manifold, the machining to level the manifold should take care of that, also check for any cracks on intake while it’s off . Good luck on your project I have been there trying to track down issues on my cars, can get frustrating.
 
Thanks for the words of encouragement. I can't go any further until the manifold is machined and returned. I'll let you all know the outcome. (Hopefully a happy one!)
 
Yes restoring or even working on car can be like being pushed face down in a mud puddle and kicked in the head with an iron boot.Currently trying to fit new back panel on my car just to find out it’s been all welded in !
 
Got the machined manifold back and installed it. Although the car does run better, it still is not a smooth running engine. My Coupe (which has 30K miles on the rebuilt engine) runs like a finely tuned clock. This car runs like a person in need of medical treatment of some kind. The carb. is the one off of my Coupe, so I know that's definitely good. I've checked and reset the points, checked timing, worked over, gapped (to .035) the 3X spark plugs, and everything else I can think of, but no dice. It's still a very uneven idling engine. It seems to run pretty good at a higher rpm. It definitely doesn't have as much pep as my Coupe. Would that be considered normal for the heavier town sedan compared to a Coupe? I have the uneasy feeling I may be headed for an engine rebuild.
 
Hello again, do a compression check and see what it is, if valves aren’t seating correctly would cause poor running, the compression check will also detect a head gasket leak also sometimes it goes between 2 and 3 causing low compression. I would do this before taking anything apart.
 
gdmn852 said:
Hello again, do a compression check and see what it is, if valves aren’t seating correctly would cause poor running, the compression check will also detect a head gasket leak also sometimes it goes between 2 and 3 causing low compression. I would do this before taking anything apart.
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I'm almost afraid of what I might find, but you're right, a compression check is the next logical step to take. Will get back here with the results. Thanks.
 
ampico-kid said:
Have only had the car for two weeks, and haven't run it out on the road long enough or hard enough to bring it up to a normal running temperature. With the stop/stall issue in the forefront of the problem list, I haven't played with the GAV other than to get the car started and then open it up a bit more.
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I as well am curious to where you run your GAV once your up and running. What about your other Coupe that runs and drives good? Once it’s warmed up and running where do you have your GAV set?
 
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