How does an electric choke work?

[MaineShark]

Okay, I think I've figured out / guessed how a hot-air choke works: as the exhaust heats up, the heat exchanger heats the bimetal coil, which opens the choke. Correct?

If that's the case, how does the electric choke work? Everything I've seen says to simply connect it to switched power, which would seem to mean that the choke is always being heated, and should always be open. Or is there sufficient delay in the coil's response to heat, that it doesn't open too fast? If that's the case, what happens if the key is switched on, but the engine isn't immediately started?

The next question: is adding an electric choke to my current carb simply a matter of unbolting the hot air choke, and bolting on the electric choke unit (and supplying power)? Or is it more involved? I'm planning on getting an intake that doesn't have connections for a hot air choke, so I need some other method.

The last question is: would there be any benefit to getting one of those universal manual choke conversion cables that NAPA sells, and simply controlling the choke, myself?

Joe

 

[JohnZ]

Yup, hot-air-tube choke works as you described. Electric choke draws current all the time the ignition is "on", which expands the bimetallic coil and keeps the choke open; when you shut the engine off, the coil cools down, contracts, and closes the choke. If you switch the key on and wait a minute before you crank it, the choke will already be open.

Installation of the kit is simple - just bolt it on, provide ignition-switched full 12 volts (don't use the coil + terminal, as it only gets 7-8 volts when running) and ground, and adjust the cover to get the choke operation that works best for you.

Manual chokes are OK, but they usually don't have a vacuum pull-off, and you have to remember to push the knob all the way in as the engine warms up.

 

[MaineShark]

Hmmm... that seems like a pretty lousy way to make a choke work. There has to be something better...

Are there any available choke units that contain only a solenoid, for computer control of the choke? (maybe on one of the later Q-Jets?)

If so, a thermostatic switch would allow the choke to be controlled by the actual engine operating temperature... (it would also be a good way to have an "idiot light" to remind people not to pound on the car while it's still cold)

Joe

 

[bradfordsvettes]

you really need to put an oil switch inline with the 12volt feed or the choke will open even if the car is not running the oil switch supplies 12volts after the car is running ,an electric choke is not really a bad choice
steve