automatic choke

[mckpaul]

Ok - thought I had the Q-jet automatic choke thing figured out, but too many years have gone by since I messed with one. And down here it so rarely gets cold enough to be an issue.

Tell me about that bi-metalic spring in the little housing that closes and opens the choke based on temperature. I know it as it gets warmer it moves/rotates enough to allow the choke to open completely, and when it's cold it moves the other way to close the choke, and I know about the choke vacuum pull off valve and all that when the engine starts etc. Guess I always viewed the choke spring assembly as "electrically assisted", the one wire connector bringing power to the unit, using voltage to heat the coil and make it move more, have more travel, other than just depending on heat from the engine. The wire on mine was disconnected when I got it, and if you set it where it closes when cold it never opens completely when the engine is warm, and if you set it where it is open when warm, it never closes enough to give you choke to start when it's cold out. I read +12 volts on the wire, but when I connect it the voltage drops to 0 volts, and there is an indicator light on the dash that says "Choke" that comes on when connected. Guess I'm reading the voltage on the open wire back through the bulb. So this one wire connector is actually just a ground trigger for the dash light that goes open when it gets warm or what? Does the bi-metalic spring strictly work off the heat from it's surrounding area? Used to be that way years back, but those were bolted directly to the intake.

Can someone tell me how this really works?