Carburetors are getting older and the old hot air and divorced chokes are getting harder to fix, or replace due to part availability.
What is an Electric Choke?
An electric choke is a heating element that is installed inside the carburetor, typically near the choke valve. When the engine is started, the electric choke heats up, which helps to vaporize the fuel in the carburetor and make it easier for the engine to start. Unlike traditional manual chokes, which require the driver to physically manipulate the choke valve, electric chokes can be controlled automatically, making them much more convenient to use.
Hot Air Choke
This type of choke gets heat from the exhaust manifold via a stove pipe routed from the manifold to the carburetor choke housing. Vacuum inside the choke housing pulls the hot air from the stove pipe into the choke housing, heating up the thermostat and opening the valve.
Divorced Choke
With this type of choke, the thermostat is mounted in a recess built into the intake manifold. The thermostat gets heat directly from the intake. A rod is attached to the thermostat and the choke valve. As the thermostat heats up, the rod opens the choke. These rods are for the most part non existent these days. Many of the thermoses are also no longer available.
What are the signs that your choke is having problems.
The choke in a carburetor plays a key role in controlling the engine's air-fuel mixture, especially during cold starts. It closes off the air supply to help enrich the fuel mixture and warm up the engine faster. If the choke isn't functioning correctly, you may observe the following symptoms:
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Difficulty Starting the Engine: If the choke doesn't close as it should when the engine is cold, it may cause starting difficulties because the air-fuel mixture may be too lean.
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Engine Running Rough or Stalling at Cold Start: Even if you can start the engine, a faulty choke can cause the engine to run roughly or even stall shortly after startup because the fuel mixture isn't rich enough for cold running conditions.
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High Idle RPMs: If the choke stays closed even after the engine has warmed up, it can cause the engine to idle at higher RPMs than normal. This is because the rich fuel mixture can lead to faster-than-normal combustion.
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Poor Fuel Economy: A choke that is stuck closed will enrich the fuel mixture unnecessarily, causing the engine to use more fuel than it needs, leading to poor fuel economy.
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Black Smoke from the Exhaust: If the choke is stuck closed, the engine will be receiving an overly rich fuel-air mixture. This can lead to incomplete combustion and produce black smoke from the exhaust.
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Fouled Spark Plugs: A choke that's stuck closed can cause the spark plugs to become fouled due to the excessively rich fuel mixture. Over time, this can lead to poor engine performance and other problems.
Our Electric Choke Conversion Kit
While it is possible to replace some hot air chokes to a standard electric thermostat they just aren't as accurate as our conversion kit. The standard electric thermostat uses only the voltage coming through the wire heating up the thermostat over time, regardless of how warm the engine is. Our conversion kits use a rheostat mounted to the intake manifold sensing the heat and adjusting the amperage to the thermostat.
What do you need to use the conversion kit?
The choke housing must be there. Carburetors with a manual choke may not have the housing installed. If the choke was modified from a hot air to a manual, then there is a good chance the parts necessary for the conversion are still there.
For the hot air types mounted on the carburetor, the image above illustrates the bare minimum that you need to install an electric choke kit. The end of the thermostat coil will use the thermostat tab as depicted to close the choke valve. The pulldown should also be in place. The pulldown is used to open the choke valve slightly when the choke is closed (cold) and you tromp on the gas. Otherwise the engine will choke out.
If your old choke was a divorced choke, then the intake manifold and carburetor must match the original. This is due to the different lengths from the thermostat up to the choke valve.
This isn't a problem if you have an integral type of thermostat. Integral - mounted on the carburetor, not on the intake.
If you have a spacer under the carburetor and you have a divorced choke type, the choke rod length may not be what is needed.
Do you need to block off the old hot air port, or vacuum source?
No, but blocking the hot air inlet at the thermostat housing would be best so cold air isn't getting sucked into the housing.
Direction of the thermostat
In the picture above, the thermostat tab moves clockwise to close the choke valve. That means you need a thermostat the turns counter clockwise when heated up.
Installation Instructions
All of our conversion kits include a step by step instruction sheet.
