Carburetor choke thermostat heater

[Illahe]

Hello all,

looking for some input regarding the electric assist portion of a Holley 2bbl model 2245's carburetor choke thermostat heaters "eclectic assist" function.

My sons 360 Power Wagon is equipped with this choke. Currently there is no power hooked up to the element, but I see some sort of porcelain electrical device (ballast(?) on the intake manifold that is not being energized during the run ignition position (no wires feeding the device are present).

The truck doesn't like to start with the choke butterfly fully closed. If we open the butterfly 1/8" she fires well and warms right up and the choke butterfly returns to a non restricted position when the engine achieves operating temperature.

I see no adjustment for the choke butterfly other than "tweaking" the actuating rod, is this correct?

 

[Vaanth]

Hello all,

looking for some input regarding the electric assist portion of a Holley 2bbl model 2245's carburetor choke thermostat heaters "eclectic assist" function.

My sons 360 Power Wagon is equipped with this choke. Currently there is no power hooked up to the element, but I see some sort of porcelain electrical device (ballast(?) on the intake manifold that is not being energized during the run ignition position (no wires feeding the device are present).

The truck doesn't like to start with the choke butterfly fully closed. If we open the butterfly 1/8" she fires well and warms right up and the choke butterfly returns to a non restricted position when the engine achieves operating temperature.

I see no adjustment for the choke butterfly other than "tweaking" the actuating rod, is this correct?
View attachment 1716480858

The electric heat on the choke does not come into play during engine cranking. The choke assist unit powers the heating coil in the choke thermostat after the engine is running (or whenever the ignition run circuit is powered).

The choke butterfly is generally closed when the engine is cold at start up. When cranking, the air flow in the carburetor throat pulls the butterfly plate open slightly. When the engine started, the vacuum kick pulls the plate open further. The choke thermostat then allows it to open the rest of the way as it warms up.

To adjust the butterfly initial opening, the linkage can be bent slightly to set the opening. If the choke thermostat is too stiff mechanically, it can hold the choke plate too tight. Tweaking the thermostat coil or its rod can allow it to be looser, but a fresh choke assembly might be required depending on the condition.

For more information about the choke assist control, refer to the following:

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An electric assist choke was used on 1973 - 1989 Chrysler carbureted engines. The choke thermostat contains a heating element which is controlled by a control device powered by the Ignition Run circuit. The choke heater connects to one terminal on the device, and the other terminal is connected to the Ignition Run circuit, before the ballast resistor. The control is mounted on the intake manifold on small blocks or on the head on big block and slant six engines.

Below ~58 degrees Fahrenheit the dual stage control applies partial power to the choke heater element. Above ~68 degrees Fahrenheit, it applies full power to the element. At ~130 degrees Fahrenheit it turns off power to the element. This provides for a slower choke opening in colder temperatures, and faster opening in warmer temperatures, and no electric heat at the choke during a restart when the engine is already warmed up.

A dual stage and single stage, with a lesser degree of control, was used, depending on the application. An earlier version of both dual and single stage was used 1973 - 1976 when it was redesigned with different internal control and external format.

The four styles of electric control units are listed in the following and shown in the following image:

• Chrysler 3656730, 3698357: 1973-1976 single stage.
• Chrysler 3755750, 3755770: 1974-1976 dual stage.
• Chrysler 4049799: 1977-1989 single stage.
• Chrysler 4049777, 4091034: 1977-1989 dual stage.

The controller is mounted on the intake manifold on small blocks or on the head on big block and slant six engines. The following image shows one mounted:

To prevent power from being applied to the choke when the engine is off, but the key switch for Ignition Run is on, Chrysler added an oil pressure switch in 1979 which cuts power when there is no oil pressure.

The 1979 - 1989 switch (Chrysler number 3231347, 3747431, 4186352) is a three terminal switch with one terminal connected to the dash oil light and the other two terminal in the circuit wiring to the choke control.

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[Illahe]

The electric heat on the choke does not come into play during engine cranking. The choke assist unit powers the heating coil in the choke thermostat after the engine is running (or whenever the ignition run circuit is powered).

The choke butterfly is generally closed when the engine is cold at start up. When cranking, the air flow in the carburetor throat pulls the butterfly plate open slightly. When the engine started, the vacuum kick pulls the plate open further. The choke thermostat then allows it to open the rest of the way as it warms up.

To adjust the butterfly initial opening, the linkage can be bent slightly to set the opening. If the choke thermostat is too stiff mechanically, it can hold the choke plate too tight. Tweaking the thermostat coil or its rod can allow it to be looser, but a fresh choke assembly might be required depending on the condition.

For more information about the choke assist control, refer to the following:

---

An electric assist choke was used on 1973 - 1989 Chrysler carbureted engines. The choke thermostat contains a heating element which is controlled by a control device powered by the Ignition Run circuit. The choke heater connects to one terminal on the device, and the other terminal is connected to the Ignition Run circuit, before the ballast resistor. The control is mounted on the intake manifold on small blocks or on the head on big block and slant six engines.

Below ~58 degrees Fahrenheit the dual stage control applies partial power to the choke heater element. Above ~68 degrees Fahrenheit, it applies full power to the element. At ~130 degrees Fahrenheit it turns off power to the element. This provides for a slower choke opening in colder temperatures, and faster opening in warmer temperatures, and no electric heat at the choke during a restart when the engine is already warmed up.

A dual stage and single stage, with a lesser degree of control, was used, depending on the application. An earlier version of both dual and single stage was used 1973 - 1976 when it was redesigned with different internal control and external format.

The four styles of electric control units are listed in the following and shown in the following image:

• Chrysler 3656730, 3698357: 1973-1976 single stage.
• Chrysler 3755750, 3755770: 1974-1976 dual stage.
• Chrysler 4049799: 1977-1989 single stage.
• Chrysler 4049777, 4091034: 1977-1989 dual stage.

View attachment 1716480869

The controller is mounted on the intake manifold on small blocks or on the head on big block and slant six engines. The following image shows one mounted:
View attachment 1716480870

To prevent power from being applied to the choke when the engine is off, but the key switch for Ignition Run is on, Chrysler added an oil pressure switch in 1979 which cuts power when there is no oil pressure.

The 1979 - 1989 switch (Chrysler number 3231347, 3747431, 4186352) is a three terminal switch with one terminal connected to the dash oil light and the other two terminal in the circuit wiring to the choke control.

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Thank you!

 

[RedFish]

That electric assist was added to the same coiled metal choke driver only to satisfy the EPA.
The ceramic box has 2 of bimeyal beams wound with ni-chrome wire similar to what is found in the gauge voltage limiters.
The thing never was water tight. Moisture would kill them. Odds that one still functions properly today are very slim.
The choke will continue to work without the electric assist, just open a little slower.