62 fuel cap question

[Joe L.]

Re: 62 fuel cap question

Joe I have AIMs 1957, 1959, 1961, 1962. Here is the data.

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1957 AIM Sec 8 Sheet 2 Dated 9-15-55

CAP 3742472

The photo of the tank shows a 90* vent pipe on tank top and vent hose Part# 3742279. Of interest is Note 12 at Part# 274684 "Clamp" for the vent hose to the tank 90* nipple. The note is dated 3-25-57 " 274684 ADDED ".

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1959 AIM Sec 8 Sheet 2 Dated 4-19-57

CAP 3751027

OPT 3751022, 3764641 (no date reference)

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1961 AIM Sec 8 Sheet 3 Dated 5-5-60

CAP 3751027

Note 9 Dated 3-9-61 34727
3751022 3764641 OPTIONAL CAPS REMOVED

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1962 AIM Sec 8 Sheet 3 Dated 4-28-61

CAP 3751027

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This thread from several years ago may also have some relative info.

https://www.forums.ncrs.org/showthre...vented-gas-cap

Rich------

Thanks. I'd forgotten about that earlier discussion of the caps.

As I mentioned in that discussion, the GM #3751027 was the last non-vented cap cataloged by GM for a C1 Corvette application and it was discontinued from SERVICE in August, 1960 and replaced, successively, by GM #3772749, GM #3787291, GM #3814436, and GM #14002439, all of which are vented-type caps. The latter is still available and cataloged for 1953-62 Corvette SERVICE to this very day.

Apparently, the GM #3751027 "lived on" in PRODUCTION for 2 years after it "died" in SERVICE.

[Joe L.]

Re: 62 fuel cap question

All------


It seems very strange to me that GM would have used a non-vented fuel cap in PRODUCTION for most C1 Corvettes but, for the last 57 years, offered only a vented type cap in SERVICE. From what can determine, Stant, a major supplier of fuel caps to GM (and other brands) does not even make a non-vented type cap for these (or, most other) applications. Thinking about it for awhile, I think I might have it figured out. In general, a vehicle which originally was equipped with a non-vented cap due to the fuel tank being otherwise vented, could later be equipped with a vented style cap with no problems. C1 Corvettes might be an exception due to the leakage problems under certain conditions as described by others. On the other hand, vehicles originally equipped with a vented fuel cap could face disastrous consequences if later equipped with a non-vented type cap (e.g. fuel tank collapse). So, perhaps GM and Stant decided they would offer only a vented type cap in SERVICE to prevent a non-vented type cap being mistakenly installed on a vehicle requiring a vented cap.

If a non-vented cap is desired and original configuration is not an issue, a dollop of JB Weld as has been mentioned (or, a self tapping screw) will easily convert a vented cap to a non-vented. Be sure the tank's venting system is working properly before doing this, though.

[Terry D.]

Re: 62 fuel cap question

Isn't there a difference between "vented" and "vented, anti surge". I was told years ago that a vented cap would leak on a C1 but a vented anti surge would not. Any truth to this?

[Richard M.]

Re: 62 fuel cap question

Isn't there a difference between "vented" and "vented, anti surge". I was told years ago that a vented cap would leak on a C1 but a vented anti surge would not. Any truth to this?

John explains here. Air can vent into tank but prevents fuel from going out the vent.