Gas Cap

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APK

APK

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I bought a gas cap off of ebay for my 1972 Dodge Dart Swinger with a 318 engine. They gas cap does not fit, the locking tabs are wider than the slots on the mouth of the gas tank. The seller stated in his listing that this is a non vented cap and fit 1972 Dodge Darts. But when I inquire why the cap did not fit he said that my car needs a vented cap.

Question, did the Dodge make 1972 Dart and different gas tanks that require a vent or non-vent gas cap?
 
Generally all gas caps are vented on mopars with carburators. Without the vent, as you sucked gas out of the tank the tank would also get sucked in. Think of a paper bag you blow into, if you inhale from the bag after filling it, it collapses. The cap you bought is likely a 74-76. The filler necks changed slightly when the unleaded flapper door was added in late 73/74.
 
'72 & later is internally different from the prior years .
By 1972 , all MoPars had vapour canisters , and thusly different fuel tank vents .

The cap you're describing sounds like a '70-'71 cap , a '67-'69 cap , or even a c.'63-'66 cap .

IMO , you're dollars ahead by purchasing a 'generic' replacement , removing its screwed-on handle , tossing that irritating warning tag in the dumpster , laying down a coat of etching primer ( except on the plastic handle ! use regular primer here ! ) , painting the cap body colour , reassembling and then ---- >:burnout:
 
Since the vapor canister is long gone from my'72 Duster, is there a way to vent the gas cap? Maybe a small hole drilled in that inner piece? I wouldn't plan to fill it up into the tube.
C
 
All kinds of hashed-up misinformation being presented in answer to this rather simple question. LH23H2R's is the only one that's factually accurate so far.

A "vented" fuel cap, by definition, is one that has an unrestricted passage from inside to outside. Most Mopars, including all A-bodies, don't use vented caps. '70-up (California) and '71-up (50-state/Canada) cars use pressure-vacuum caps, which have valve-controlled breathing in both directions, but these are not "vented" caps (wrong term for the cap).

See here for discussion of gas cap interchange ('72-'76 A-body, in your case).

And no, venting the gas cap does not substitute for the removed (why?) vapor canister.
 
And no, venting the gas cap does not substitute for the removed (why?) vapor canister.

Hi Dan, my car was a basket case when I got it. There was no vac canister in the car or boxes. At this point I am only searching for various options I might have.
C
 
The non-ECS 70-down are "non vented" and have 3/8" wide tangs. 70/71 models with ECS and 72+ models will have a "vented" cap with 1/4" tangs. I am going through this problem as well which is why I am posting on this old thread.
 
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Belvedere66 said:
70/71 models with ECS and 72+ models will have a "vented" cap with 1/4" tangs.
Click to expand...

No, '70+ cars with ECS do not have vented caps. They have pressure-vacuum caps. It's not the same; see here. Also, the '70-'71-with-ECS gas cap is not the same as the '72-'76 cap.
 
clhyer said:
Since the vapor canister is long gone from my'72 Duster, is there a way to vent the gas cap? Maybe a small hole drilled in that inner piece? I wouldn't plan to fill it up into the tube.
C
Click to expand...

That's what I did, I was having a small vent issue when I switched to EFI. I drilled a hole through the inner piece and all my issues went away. Probably not the best solution, but it worked and cost nothing.
 
72Duster440 said:
That's what I did, I was having a small vent issue when I switched to EFI. I drilled a hole through the inner piece and all my issues went away. Probably not the best solution, but it worked and cost nothing.
Click to expand...


Running a vented (drilled) cap on a Mopar with a fender filler like these all use is an invitation for gas down the side of your paint job. If you are not using the canister, and the rest of the system is intact, all you really need do is to run the front tube "up high" and either end it "overboard" or plumb it into the air filter bonnet. An alternative is to "build" a likeness of the 69/ earlier vent tube in the filler neck.

All that needs happen for fuel all over the side is a full tank, a hot day, and parking someplace like on a one way street with the filler side of the car tilted low.
 
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