Quote Originally Posted by myoldyourgold View Post
The valve that he adjusts is a crude carb at least that is my take on it. He is adjusting the amount of air. Looks like a needle valve. I could be wrong.
Yeah , I think you're right, the valves teed on top of the bubbler. Looking again can't be too much vacuum with those hoses, those hoses look soft and would probable collapse with too much Vacuum.