The 1 barrel carb I have is from a 78 GMC truck with a intagrated head 250. I am wondering what the electric selanoid for the idel gets hooked up to. Is there some switch or is a keyed 12 volt like a choke. After I wire it up how is it to be adjusted? Should I just ditch it and put a screw in its place? Sorry for all the questions. Thanks

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.

I was wondering about the bowl vent myself. On the the carb that has the selinoid it just had a rubber plug over it, but I do not know if this is correct or not. I have another carb that does not have it and I will probably take it apart and see were it vents off to.

Could just vent to atmosphere with a hose,as long as no dirt gets to the carb.Should go to carbon canister though.