Holley Choke Thermostat

[dartjitsu]

Hello all - I'm not a mechanic or have any real experience working on cars, but I think I've managed to diagnose a problem down to the Holley choke thermostat on my '72 dart swinger (225 /6).

It turns on, but after a few minutes, the engine will die. So I'll fire her back up and play with the choke and I'm able to keep the car running by holding it in a certain position. So I'm thinking there is some kind of temperature regulating issue as the choke warms up from the manifold.. There is a wire attached to the choke thermostat - can someone explain it's purpose and if you think I'm even on the right track? I ordered a new one, it was like $36 and it's really easy to replace.

 

[Mattax]

Is this a replacement carburetor?
If so, the choke may open only when the electric power heats the choke.

If its factory or direct factory replacement, the electric power is only a choke assist.

A choke should work like this.
Cold start, move the throttle to set the choke. Choke closes almost completely and the throttle stop moves to the fast idle position.
Start engine.
Vacuum opens the choke slightly.

As the intake manifold warms up (or the electric heating unit warms) the bimetal coil unwinds.
Then when the throttle is tapped the choke will open further and the fast idle cam will rotate out of the way.

 

[SIX225]

If you have a wire attached to the choke, it not the original to 1972. Coupe of years right in there, the choke pocket was was directly in the exhaust port. Guessing your manifold was changed at some point.

 

[dartjitsu]

Is this a replacement carburetor?
If so, the choke may open only when the electric power heats the choke.

If its factory or direct factory replacement, the electric power is only a choke assist.

A choke should work like this.
Cold start, move the throttle to set the choke. Choke closes almost completely and the throttle stop moves to the fast idle position.
Start engine.
Vacuum opens the choke slightly.

As the intake manifold warms up (or the electric heating unit warms) the bimetal coil unwinds.
Then when the throttle is tapped the choke will open further and the fast idle cam will rotate out of the way.

I did replace the carburetor a while back - it's now a Holley single-barrel. Thank you for your explanation of how the choke works, it really helped me.

 

[dartjitsu]

If you have a wire attached to the choke, it not the original to 1972. Coupe of years right in there, the choke pocket was was directly in the exhaust port. Guessing your manifold was changed at some point.

When I bought the car, this was all in place already. Does the wire from the choke indicate that it is an electric choke?

 

[Charrlie_S]

It might not be a choke problem. The engine might be running lean (carb issue, vacuum leak), and by manually holding the choke part way on it is richening up the mixture, allowing the engine to run.

 

[Mattax]

When I bought the car, this was all in place already. Does the wire from the choke indicate that it is an electric choke?

Either fully electric or electric assist.

Is there location to attach a connecting rod to a choke control in the intake manifold?

 

[Mattax]

Factory Holley 1920. All mechanical choke.

Choke control goes in exhuast manifold

Can you post photos of what is on your car?

Choke valve should be fairly closed when starting, and wide open when the engine is warmed up.
In a warm climate can get by with choke open all the time.

If you must wire in an electric choke, use a piggyback connector so none of the original wiring gets altered and damaged.

I don't like adding electric chokes because it adds a lot more electrical load to the run wiring.

 

[Mattax]

Digitized Service Manual
www.mymopar.com
Go to Service Manuals

 

[dartjitsu]

It might not be a choke problem. The engine might be running lean (carb issue, vacuum leak), and by manually holding the choke part way on it is richening up the mixture, allowing the engine to run.

Ok, I see what you mean