Northwest Nova

Early Nova Gas Cap Not Fit?

October 23rd, 2021  |  NWN  |  They're Not All The Same

Quite a common issue people encounter is a replacement gas cap not fitting on their 1962 - 67 Nova. It will either not screw on or fit quite loose and not seal. Putting aside damage to the filler neck, also common, the issue is usually caused by one of two things:

1. The wrong year (i.e. design) gas cap being used.
2. The wrong year filler neck installed in the car — not matching the correct gas cap.

GM used two different gas cap designs on the Chevy II between 1962 and 1967¹. This also means there are two different style filler necks. The breakout is 1st design 1962 - 64 and 2nd design 1965 - 67. The difference is the depth of the "cam" or "neck" on the gas cap, as can be seen in the pics below. The "short" or "shallow" 1st design cap was used in 1962 - 64, the "long" 2nd design cap in 1965 - 67. Each design also has a corresponding filler neck. Why GM made this design change we do not know, probably something related to better sealing.

NOTE 1. There were five different gas caps available from GM for the Chevy II in the 1962 - 67 period. We break these out here.

 How Can My Car Have the Wrong Filler Neck?

The two filler necks look identical and are completely interchangeable. It is not uncommon for the car to have the wrong year filler neck causing the correct gas cap not to fit. These filler necks can be damaged in collisions, rust badly or were tossed on "race cars", so many have been replaced by this point in time. Most people did not know the necks were different 20 or 30 years ago, so grabbed the wrong one at the junk yard or swap meet.

It is worth noting people will use the 1965 - 67 filler neck on the earlier cars so they can use the reproduction locking bowtie gas cap. Though there was a 1st design or "early" locking gas cap available from GM in the 1960s, one is not currently reproduced. Good used and NOS versions of these caps are extremely difficult to find.

 Be Aware...

The first run of reproduction filler necks, probably 20 years ago, had issues with gas cap fitment. Gas caps would not sit flat, sit with the handle properly horizontal to the body or in some instances flat–out install. The problem were the necks, not the caps, and the issue was resolved some time ago. These necks are still floating around though, so something to be aware of.

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Last updated Jan 10, 2022