It was supposed to be powered when engine was running and then when engine is shutoff it would allow throttle to close a bit more to prevent the engine from dieseling. I think Chilton's lists an idle speed with solenoid plugged in and unplugged.
Definitely a band-aid for trying to meet emission standards.
If you don't need it you could remove it or leave it unpowered and adjust idle by turning whole solenoid.
Can anyone say how to handle the bowl vent on these carbs were it was meant to have a hose running to the charcoal cannistor? Most old carbs have little vents inside air cleaner.
