Gas cap - Vented or Not

Now for the correct answer

NO A bodies used a vented cap at least between 67 and 69 NOR did they later in the "sense of the word" "vented"

In the years starting with CA in 70 SOME had "evaporative emissions controls"

These ALSO DID NOT use a true vented cap NOR was the cap used "for a vent" in normal operation. they are sometimes mistaken for a vent BUT IN REALITY they are known as "pressure vacuum" caps and had relief valves to allow pressure to equalize, as the name implies, both pressure and vacuum BUT THE caps WERE NOT "vented" in the normal sense

Up through 69 (and beyond Federally) ---Tanks were vented using a simple tube welded into the filler neck

Whichever cars had the evap emissions--and these systems CHANGED somewhat nearly every year after--THE TANKS WERE VENTED through a long 1/4" tube going from the tank up front, later incorporated into the "carbon can" system and earlier, simply teed into the valve cover breather cap. THIS VENT TUBE IS THE TANK VENT

You can confirm all this by downloading the various service manuals over at MyMopar and reading the sections on carburetion, fuel tanks and emissions

Caps changes over the years posted by a member here NONE OF THESE ARE VENTED in the "operational" sense

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The vent system/ evaporative emissions system

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