Here are the pictures of the valve. According to my Seloc manual it says "In order to prevent the engine from stalling during high vacuum conditions, a deceleration (gulp) valve is used on all carbureted Ford engines. Air is allowed to flow into the intake manifold, entering the air/fuel mixture so as to lean out the rich condition frequently created by high vacuum when the throttle valves are closed on rapid deceleration. Sudden vacuum acts to draw down the diaphragm in the valve, opening the valve and allowing air to flow through the screen and into the manifold."
She made us proud and boy did we have fun.