Your fuel line should have a brass ball ferrule installed on the fuel line
after you slip on the hex fitting:
https://www.snydersantiqueauto.com/p...9362&cat=41707
For this set up to work properly, you need to have between 1/8" to 3/16" of fuel line protruding past the ball ferrule. Slip the assembled fuel line into the threaded opening of the carb and hold the fuel line in place while carefully tightening the brass hex fitting. By tightening the brass fitting, it compresses the ball ferrule around the fuel line to essentially clamp it in place so that it cannot pull free. I hope that makes sense.