or (Ford) Gulp valve or anti-backfire valve, AMC Decel-valve.....used on 70's era cars to prevent backfiring when letting off the gas. Jeep used them, cant remember a Mopar application. Question: is the vacuum pod supposed to hold a vacuum? My little Mazda truck wont idle and I found this part (I bought it NOS 7 years ago and put maybe 1000 miles on it) wont hold a vacuum so I assume this is the vacuum leak or part of it. I guess its supposed to open a large air to exhaust manifold feed upon deceleration to dilute the rich A/F when you snap the carb shut. This part is N/A today so I got to figure out what I can do. Seems the 3/4" passage goes right from the air cleaner through the valve right into the intake manifold where the PCV valve is on my intake. So I'm guessing there should be a leak free seal at the outlet to the intake manifold as well as the vacuum line to the control diaphragm. Both seem to be leaking slightly although the big one is leaking less than the small 1/8 vacuum control line. Upon higher than idle vacuum (25" decel or right off the gas) the valve should open momentarily and dilute the intake with air preventing an explosive ratio. Vacuum drops, the valve closes and it stays closed until it decels again.