71 Demon 340 gas cap/ filler neck correct?

ricomondo · Jul 10, 2023

Not sure what cap I need for the Demon 340? Current cap appears to be 72-up?
I need to find the “insert” that I can change out so the cap can seat properly. Purchased a couple of caps from Vans, but neither fit.
Also how about the filler neck does it look correct?
Thank you!

Oldmanmopar · Jul 11, 2023

You need to find a 71 cap. Or a 70 Duster neck. 72-76 cap will not work on your fill tube and a 72-76 fill tube will not fit your car. 72 -76 fill tubes sit on the outside of the quarter. 70 and 71 go on the inside of the quarter like the one you pictured. 70 and 71 take a different cap and do not interchange.

A Dart and Scamp fill tube will not fit the Demon or Duster. They have 4 screws and have a sharper bend.

The pictures you posted of the caps were pics I posted years ago. I still have most of the caps for reference and tubes

Last picture is of the cap you need. Second last is a 70 cap you will need a 70 Duster only fuel tube with the vent on it to use a 70 cap. 71 and 70 are the only interchangeable tubes for a 71 Demon or Duster.

The recess on a 70 and 71 Duster Demon quarter panel is shallow compared to the 72 to 76 cars