Need help adjusting my fast idle cam on a 4bbl Carter Thermoquad (1979 Chrysler Cordoba)

[James Watkins]

I apologize if this is an annoying question but I have no idea what I'm doing. Basically I've had an issue with the fast idle on this car ever since I bought it around 6 years ago now. The fast idle speed seems fine, as does the slow idle speed, but it stays in fast idle for far too long when I first start it. It seems to take way too long for things to "warm up" so that tapping the accelerator pedal drops the fast idle speed down to the slow idle speed. At least a minute or two on hot days and so long on cold days that I usually don't even drive the car if I can avoid it. My question is what could be causing this? I know there is a choke temperature sensor, could that be the problem? Should I replace it? Or the vacuum choke pull-off thing? Or is it an issue with the cam for the fast idle? It seems to me that it would be an issue with the car thinking it's not warm enough, since it always idles down faster the hotter it is outside. I would really appreciate some insight as to what might be causing this and how I could go about fixing it. The car runs pretty great otherwise, but this issue has been bothering me for years and years. I should have fixed it a long time ago, but carburetors kind of scare me if I'm being honest. I've only ever worked on small engine carbs and fuel injection.

Fair warning, I know basically nothing about carburetors. Especially more complicated ones like a thermoquad. I would much rather have an old pro fix this, but unfortunately that's not really an option at the moment. So any insight would be greatly appreciated. Thanks.

 

[4406bbl]

Probably one of 2 things, the heat riser valve, if it has one, in the right exhaust manifold is stuck, or inoperable for some reason, try lubing it with a penetrant like pb blaster or mopar penetrant/heat riser solvent. What you are calling a sensor is actually a heating coil down in the choke well. Apply 12 volts to it and make sure it heats up. There should also be a white choke control module to the rear of the carb on the right side that could be bad.

 

[4406bbl]

You may also have a different style heat control that isround. Either way it should have 12 volts in and 12 volts out cold. I would not mess with the carb until you know everything g is getting hot at the choke well.

 

[493 Mike]

The TQ has a number of adjustments that have to be performed in the correct order (like a lot of other carbs). Check the FSM or a Motors manual for the specs and sequence. But, as previously stated, check the choke operation first.
Mike

 

[James Watkins]

The TQ has a number of adjustments that have to be performed in the correct order (like a lot of other carbs). Check the FSM or a Motors manual for the specs and sequence. But, as previously stated, check the choke operation first.
Mike

Will do, thanks for the tip. I am much more comfortable working on anything other than that carb, so hopefully something with the choke will do the trick.

 

[James Watkins]

You may also have a different style heat control that isround. Either way it should have 12 volts in and 12 volts out cold. I would not mess with the carb until you know everything g is getting hot at the choke well.

I'll take a look and see what I can find out later today. I don't plan on messing with the carb if I can help it. Like I said, the car runs pretty good and I don't know what I'm doing. So I'd like to avoid making it worse. Thanks for the help.

 

[James Watkins]

Probably one of 2 things, the heat riser valve, if it has one, in the right exhaust manifold is stuck, or inoperable for some reason, try lubing it with a penetrant like pb blaster or mopar penetrant/heat riser solvent. What you are calling a sensor is actually a heating coil down in the choke well. Apply 12 volts to it and make sure it heats up. There should also be a white choke control module to the rear of the carb on the right side that could be bad.

View attachment 1615525

I hadn't heard of the heat riser problem before, so I'll definitely look into that one. Same goes for the choke control module. But as for the "sensor" what am I looking for in terms of heat? Do I need to measure how hot it's getting, or just make sure that it's at least doing something?

Thanks for the tips. I'm going to get to work later today and see what I can find out.

 

[4406bbl]

It gets real hot real fast, not something to hold in your hands. It is a heating element not a sensor looks like a beverage heater.

 

[4406bbl]

The control unit is the sensor.