The original hot air choke uses a metal spring to move the choke from closed to open position. Actually the thermostat is wound tight against the choke shaft closing the choke. Hot air is brought up from the exhaust manifold to the choke housing through a hot air tube. A small vacuum port feeds vacuum from the intake up through the carburetor and into the choke housing, which helps draw the hot air up through the hot air tube. As the choke thermostat heats up, the spring unwinds letting tension off of the choke shaft and the choke valve opens.
The choke piston is used to slightly open the choke valve when tromping on the gas while the engine is cold and the choke is closed. This piston does not use any seals, or O rings and needs to glide smoothly.
We offer electric choke conversion kits to replace the original equipment hot air style chokes on both integrated (attached to the carb) and divorced (mounted on the manifold) choke setups.
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We do not offer conversion kits or original equipment parts for manual chokes
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The choke pull down on the Motorcraft 2100 2 barrel carburetor is operated by vacuum. When the engine is off, the choke valve is completely closed. If the valve stays this way when started, the engine will not run due to lack of air.
When the engine is 1st started the vacuum is at the highest point and pulls the pull down, down all the way. This opens the choke valve enough to let some air in.
If the diaphragm is bad the engine may die after starting and when cold.
Watch to see if the diaphragm pulls down when you 1st start the engine. If not, replace it. Also check the vacuum passage to make sure it isn't blocked.
https://www.youtube.com/shorts/ZYCrZJzrGfQ
The choke system on the Motorcraft 2100 carburetor is crucial for cold starts and proper engine operation during the warm-up period. If you're having issues with cold starts or unstable engine operation shortly after starting, the choke could be at fault. Here's a step-by-step guide to diagnose Motorcraft 2100 choke problems: