Man are we discussing this thing to death or what.
The vehicles that have no air pump rely on usable oxygen from the exhaust itself. When you release the throttle there is a low pressure wave in the pipes and free oxygen pumped through the combustion chamber is drawn into the cat to assist the burn. To this end some of the vehicles (big 8 Chrysler products come to mind) use a one way check valve ported to the breather and directed to the cat.
I said it once, I say again. Go cat free and re-test your emissions.
1971 was a good year to be a car.
cats were
not required and the emissions test was more lenient.
btw I checked with Va State Police who stated "If your car is registered as a 1971 vehicle it has to meet 1971 standards."
This is supposed to be the case in all 50 states, the territories, and D.C.
Good Morning, S.
