All the US cars were required to have the evaporation from the tank filtered through a charcoal filter. #15 in the diagram.
The "breather or tank vent" was attached to the top of the fuel tank with the part we are talking about. #12 in the diagram.
At first it is just a vent with a screen with a fabric attached internally.
At some future point it was changed to a vent with check valve installed into it to prevent or reduce the amount of fuel that would drain through it if the car got upside down.
My car, 4066, did not come equipped with the check valve/roll over valve. Marlins did. I doubt there is much chance an earlier car than mine had one factory installed?
It makes more sense that somewhere in between them there was a change over? Maybe it is a '74 model feature? I see very few '74s to compare features to?
I never heard about a recall to install them on earlier cars?
This is a picture of the original tank "vent".
Attachments
Images (1)
