Slant 6- Idle and Running

IIRC that CA delay solenoid prevents the distributor from snapping back to full idle advance (and causing unburned fuel) when you get off the throttle, sort of bleeds it off over about 3-4 seconds. My Mazda had same sort of delay solenoid on it like that. the open port is in fact left open to vent to atmosphere. Mine was acting weird: it would mechanically hold the throttle open too for 2-3 seconds via the pot it controlled after you let up on it. very strange experience in a manual trans in traffic when you are feathering throttle to keep up with slow traffic. You get off gas and it keeps pulling for 2-3 seconds! Found it would not hold a vacuum so I plugged the inlet with solder (metal pot) and left the hoses on so it would pass visual here in Commifornia. made it air tight and no more delayed throttle.