I'm having a problem with the choke not closing ('78 L82, quadrajet, automatic choke). When cold, I can manually get it to close (with a slight, nickel width opening), and after pumping the accelerator pedal once, and then turning the key, the engine will fire right up. If i don't let the car warm all the way up (and the choke doesn't fully open), and let the engine cool back down, then a single press of the accelerator will close the choke again. However, if it warms all the way up and the choke fully opens, it will not close again without me manually messing with it. Can anyone suggest what might be wrong?

Thanks.

 

It's either assembled wrong or adjusted wrong, or both - both issues are common. It needs to be visually inspected, and the problem needs to be corrected along with a correct setup adjustment.

Lars

 

By "it" are you referring specifically to the hot air choke? Or something else about the entire carburetor? I had considered converting to an electric choke, but I'm not sure that will solve the problem. If you think it will though, I probably will. Thanks.

 

It's been a long time, but I think I finally solved this. Of course Lars was correct. Thanks for the write up!

Turns out everything was set up properly except the choke thermostat / coil spring. After pulling it off and ensuring nothing was broken, I reassembled it and set the tension so that it would just close the choke plate when the carb was in the fast idle mode... however it was taking it 10 minutes to drop into the slower idle mode when I drove! Thankfully from Lars's write up I learned about the nonsensical "rich/lean" markings on the choke housing... why was that ever done? After loosening the screws and rotating clockwise, the time to open dropped to just over 3 minutes. Question... should I rotate a little more clockwise to get the time down to 2 minutes? or what is the ideal time? this morning it was 3 min 30 seconds to kick down with the hood open and the ambient outside temperature / cold engine temperature of 45 F.

Also... the markings on the housing aren't even close what would seem reasonable... anyone understand this... maybe the spring just isn't warming up as fast as it should? The choke is closing just fine so it seems like its starting with plenty of tension. Here's a picture:

 

Disregard the markings. Set the choke to provide reliable idle quality during the warm-up intermediate period. Some cars need 2-3 minutes, and others need as much as 6. As long as it's neither dying nor flooding, and if idle speed in the "partially warm" mode is acceptable, you're good to go.

Lars

 

crank it all the way open and only drive on warm days...

 

You know... this car was a gift from my parents when I got my PhD in 2008. My dad found and bought it from a guy he met in a bar hahaha. He had the car for 2 years before I graduated and they kept it a secret all that time and surprised me with it at a graduation party they had for me. Then I promptly moved to LA where I had no where to park it and realized it needed a lot of work before I could even license it in California (PO took the catalytic converter off and switched the exhaust to side pipes... it would have failed the visual inspection because the exhaust was obviously not the factory exhaust -- Incidentally, I think I learned all of that on this forum way back then, but I digress hahahah). So for 10 years, I made my dad hang on to the car... he loved it so I didn't feel too bad about it. Finally I moved to Atlanta, got a garage, and now have the car and have started to learn about it and am trying to get it all tweaked up.

Anyway, that's a long way to say that the choke did not work for at least those 10 years, and probably a lot more... the choke plate was always wide open. To start it after it hadn't been driven for a day or so required about 8 pumps of the gas pedal and then hitting the key. And obviously the car never warmed up in the fast idle mode. What are the biggest concerns for operating the vehicle / engine like that in the long long long run? It wastes some fuel I'm sure... but what else? What is bad about skipping the proper warm up procedure?