71 vented or non vented gas cap e body

I have a 71 e body with a locking gas cap I want to change to an original style cap but I'm not sure if it was vented or not . It seems as though where was a change in mid year it some time. How can I tell what I have and if it was a Cali emissions car. Thanks for your input.

All 71 Challengers used the emissions cap. The 1970 Challengers used one or the other depending on where the car was destined after it was built.

No Challenger or Cuda ever came with a vented cap, none. Matter of fact no mopar came with a vented cap after 1970. They were all vented through other means.

Hmmmmmm, check your parts book before making such comments: 3404 668(on the original box) Fuel Tank Locking Cap(Vented). I have an NOS locking gas cap for my 1971 Challenger, which is what it and ALL other 1971 Challengers came with, if the cap was locking. 14-86-47, the part number there is 3404 667. The book says 1970 with ECS and all 1971 J cars.

interesting.. more input.. have had this converstaion b4 and never got answer.

School me if I'm wrong or right here. My 71 RR I think had a non vented because it had the tank in the wheel well to vent unspent gas back to this tank and back to the gas tank.

Non vented gas caps arrived with vapor recovery systems,in one form or another the fuel vapors are recovered/stored & burned off by the engine,venting is done through the recover system.

All 1970 production cars that were sold new in California had to have a vapor recovery system, which meant a sealed system and a special gas cap. All others were vented or 49 state cars. In 1971 all cars went to the vapor recovery system and basically got the California cap. 1970 also had the California only carburetors. m46rat is correct.