I was replacing the needle valve and seat on betsy the other day and as i put Carb back together ,I came to realize there was a pipe or tube sticking out of the trottle body and it had been pinched off at the top like with a visegrip or plyers.It is on the otherside of the vac advance and idle screw location.I think this is the tube that would attach to the auto choke on a bc. Truck does run well and as i am working on it i am finding the old mechanic that dad took it to just used what ever he could find from the junk yard or what ever to keep it running.