This is the valve on the side of the carburettor that provides air to the idle circuit. This valve closes when the key is off, preventing "Run on". If it doesn't open you won't idle.
This valve is on the side of the carburettor body, with a wire connected to the outer end. This is the idle fuel cutoff valve (solenoid). It is located low on the carburettor, close to the throttle arm. This valve shuts off the flow of air when you turn off the engine, to prevent "running on." Be sure the wire is connected and has a good electrical contact, and that it runs to the (+) terminal on the coil. (Also attached to this terminal is the black wire that provides power to the automatic choke, and the car's reverse lights if equipped).

Make sure that the idle cutoff valve is snugly screwed into the carburettor body (they do come loose). Be careful not to over tighten it, the threads are fine and brass, screwed into an aluminium carb body, both are relatively soft and can/will strip if over tightened.

You can test the operation of the idle cutoff valve solenoid very easily. Turn on the ignition (don t start the car), and pull off the wire on the solenoid. Touch the wire back onto the connector, and you should hear a clicking sound as the valve inside moves. If you do not hear a clicking sound, check to make sure there is power (12 volts) to the wire (small trouble light, voltmeter, etc.). Replace the solenoid if it is not working.