Question on an electric choke, I never had a working one before.

[timk225]

I just installed a Holley 350 2 bbl (80350) on my 1973 Dusters' Slant Six, using an adapter plate on an OEM iron Super Six intake.

It's a bit new for me since when I had these old cars 20+ year ago, I never had one with a functioning electric choke, just the exhaust manifold heated choke pull off rod.

Now that I have a new engine bay wiring harness and a new carburetor, it is weird having it actually work. I hooked it up today, after confirming with a multimeter that the wire was indeed switched to only be powered with the key on.

Upon its first test run, it took about a minute for the electric heat to keep the choke open and off the fast idle cam.

My only concern, weird as it may be, would be that this heating element is drawing power all the time when the key is on? I read something online about the heating element maybe having a switch built in so it shuts off power when it gets hot enough, but unless the engine heat keeps it hot enough, I think it would be switching the power on off on off on every few minutes.

 

[remytherat]

It draws a very very small current all the time the key is on. When hot it draws slightly less than when cold which is a property common to almost all materials. But no need to worry.

 

[Syleng1]

Electric chokes work great and typical set right out of the box good to go.

I’ve never measured the current but as stated it is minimal. If I were to guess maybe an amp or 2. Just make sure you have a good ground and supply wire.

And oh yea! Lots of choke oil. Most hardware stores and auto store have it in 55 gal drums.

 

[Dana67Dart]

Have you adjusted (rotated) the electric choke,? You should be able to adjust it to open sooner or later. The FSM has procedures, your carb might not be OEM to the engine or the year so look in other year FSMs

 

[timk225]

Have you adjusted (rotated) the electric choke,? You should be able to adjust it to open sooner or later. The FSM has procedures, your carb might not be OEM to the engine or the year so look in other year FSMs

I looked in the Holley instructions and saw a video on youtube. I did rotate my choke black round thing clockwise a bit so it isn't closed as hard. I've only started it up once from completely cold with the new setting and the power wire attached, but it seemed to work well. More testing this weekend.

 

[Dana67Dart]

If you just turn the key to run you can see the choke open. The engine does not need to be running.

Question... Did you power the choke off of the power to the ballast or after the ballast.

 

[timk225]

If you just turn the key to run you can see the choke open. The engine does not need to be running.

Question... Did you power the choke off of the power to the ballast or after the ballast.

Eeehhh... not sure. I recently replaced the whole engine wiring harness, and the new harness had the choke wire in it, so I just plugged it in after testing to make sure it was key switched 12 volt power.

 

[Dana67Dart]

Eeehhh... not sure. I recently replaced the whole engine wiring harness, and the new harness had the choke wire in it, so I just plugged it in after testing to make sure it was key switched 12 volt power

If it was an OEM style harness your fine

 

[Vaanth]

I just installed a Holley 350 2 bbl (80350) on my 1973 Dusters' Slant Six, using an adapter plate on an OEM iron Super Six intake.

It's a bit new for me since when I had these old cars 20+ year ago, I never had one with a functioning electric choke, just the exhaust manifold heated choke pull off rod.

Now that I have a new engine bay wiring harness and a new carburetor, it is weird having it actually work. I hooked it up today, after confirming with a multimeter that the wire was indeed switched to only be powered with the key on.

Upon its first test run, it took about a minute for the electric heat to keep the choke open and off the fast idle cam.

My only concern, weird as it may be, would be that this heating element is drawing power all the time when the key is on? I read something online about the heating element maybe having a switch built in so it shuts off power when it gets hot enough, but unless the engine heat keeps it hot enough, I think it would be switching the power on off on off on every few minutes.

Chrysler provided a method to control the factory electric assist hokes for timing of opening and disconnecting power while running after warm-up. They also provided a method of preventing choke operation with the key on, but with the engine not running. These might be useful to you in additional control of your aftermarket Holley 80350 carburetor with an electric choke.

The original Chrysler electric assist choke thermostats for carbureted engines between 1973 and ~1986 were specified to draw about three amps in operation. I set up a quick test, and tested this with several new and used choke thermostats today to confirm. The chokes tested drew 2-2.5 amps with an applied voltage of ~13.8 volts when cold. As the heating element heats up, its resistance increases and current draw is reduced to less than one amp. One test is shown in the following image, where the current is dropping. The current is being measured with the Fluke meter on the left, and applied voltage is monitored with the Sunpro meter on the right:

I don't have a Holley with electric choke, but I also measured the electric choke on an NOS Carter Thermo-Quad 9810S "Super-Quad". The Thermo-Quad choke draws ~2.5 amps with an applied voltage of ~13.8 volts when cold. As the heating element heats up, its resistance increases and current draw is reduced to ~0.5 amp. The Thermo-Quad had a higher initial surge of ~8.5 amps, which dropped to 2.5 amps in about one second.

A posting at HotRodders.com shows a similar test of a Holley electric choke:

For the first 1/4 second, it spiked at 6.5 amps and dropped to 1.3 amps. After that, as the coil heats up, it steadily dropped from 1.3 and leveled out at about .75 amps.

Chrysler did not directly wire their electric choke to the Ignition Run circuit. Nor was the choke powered continuously. Instead an electric choke control that adjusts the rate and time of power applied to the choke thermostat. The control allowed quicker warm-up for sooner choke release above 68 degrees Fahrenheit, and slower warm-up below that temperature. After two to three minutes, the control shuts off the power to the choke thermostat heating element. A single stage and dual stage unit was used. Dual stage units have a finer temperature control and have an external resistor mounted. The style of construction changed in 1977.

The electric control is a small module mounted to the intake or head. 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: 1977-1984 single stage.
• Chrysler 4049777, 4091034: 1977-1984 dual stage.

One of these original type choke controls might be used to control the Holley choke for the rate of choke pull off and to shut off the choke power after two to three minutes. I have been running the earlier style dual control unit with a Thermo-Quad 9801S with electric choke for about 25 years.


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.
The following image shows the three terminal pressure switch:

To use this switch with an oil pressure gauge, Chrysler used a tee for the switch and sending unit combined as shown in the following images:

 

[Dartswinger70]

where is it usually wired? to a key on 12volt source?

 

[Vaanth]

where is it usually wired? to a key on 12volt source?

It was originally wired into the Ignition Run circuit, before the ballast resistor (typically the blue wire on passenger cars). Any similar switched 12 volt source will work.

Original example:

 

[timk225]

That first electronic control in the picture, the 6730 / 8357 part number, looks like the one I have. It does not have an external resistor.

The wire leading to mine was broken at the connector, but since I have a new wiring harness now, I just need to get a few push-on connectors at Lowes and make a wire to go from the output to the electric connector in the carburetor itself.

So if the unit cuts off power after a few minutes, then I assume the heat coming off the manifolds of a warmed up Slant Six is enough to keep the choke open until the entire engine cools down?

 

[67Dart273]

Comparing aftermarket Holley to Chrysler OEM might be misleading. The worked in a completely different way. The Holleys so far as I know are designed to CONTINUOUSLY be powered by straight 12V off the "run" circuit.

As usual, you might want to check the "run" circuit for voltage drop, as that affects the voltage regulator. If it has anything more than about .3V (3/10 of 1 volt) you might want to look into it. If you cannot easily correct that, one way is to cut the underhood loads from the "run" wire, us the end from the bulkhead connector to trigger a relay, and switch the underhood loads with that relay, fed power off the starter relay "big stud."

 

[Vaanth]

So if the unit cuts off power after a few minutes, then I assume the heat coming off the manifolds of a warmed up Slant Six is enough to keep the choke open until the entire engine cools down?

The controller was used with the original divorced choke thermostat which sat in a well in the intake manifold, so it was exposed to more direct heat to stay open. The integral choke on the Holley carburetor might stay open due general transmitted heat through the carburetor body and ambient area, but experimenting will be required to dial in the initial and steady state choke response to see for sure.

The integral choke on my aftermarket Thermo-Quad is similar to the Holley setup and appears to have similar current flow based on the linked Hotrodder test. Mine has been working with a 1973 controller to stay open after warm-up for years from transmitted carburetor body and ambient heat. After the choke tension is brought down to a certain point from any heating, the choke pull-off, aka vacuum kick, and air flow tends to keep it open. It appears the Holley 80350 does not have a vacuum choke pull-off though.

The controller was not intended to work with the Carter integral choke, but trying it proved it works well in my case. Trying it with the similar Holley setup might prove the same. It is relatively simple to include in the choke power feed circuit, or remove if needed.