AC Oil Cap

[Mark D.]

Ralph Spears asked me to post pics of this cap with the hope someone could ID the application(s).

[Edward J.]

Re: AC Oil Cap

Mark, I think that may not be a oil cap, It may be a breather. late 50,S vintage.I know I have seen these sytle caps before.

[John H.]

Re: AC Oil Cap

Mark -

With that "push-in" neck on it, that breather cap was intended to be used in a rubber grommet in a valve cover; however, I don't recall any Corvette production applications that used a valve cover-mounted breather. Might be from an early truck or passenger car? Maybe Joe has a listing for it.

[Patrick S.]

Re: AC Oil Cap

Not a lot of production,1967 L-88

[John H.]

Re: AC Oil Cap

Not a lot of production,1967 L-88

Patrick -

Yup, forgot about that one - it used #6421284 cap asm. and #3856954 grommet, in the RH valve cover.

[Patrick S.]

Re: AC Oil Cap

John, Also in the dark ages,when the first thing you did to a big block was toss the smog gear and exhaust manifolds, you put one of these breathers in each valve cover. GM also made them in chrome.

[Joe L.]

Re: AC Oil Cap

Patrick -

Yup, forgot about that one - it used #6421284 cap asm. and #3856954 grommet, in the RH valve cover.

John-----


Curiously, I cannot find that GM #6421284 was ever available as a SERVICE part.

[Ralph S.]

Re: AC Oil Cap

It does fit in the grommet on the right valve cover where the hose to the air cleaner goes. So what is everyones decision. 1967 L-88????

[Ronald L.]

Re: AC Oil Cap

There were also some chrome plated ones, need to check the Chevelle AIM, or was it Pontiac that used it for a slight time period. ICR.

[Dick W.]

Re: AC Oil Cap

It does fit in the grommet on the right valve cover where the hose to the air cleaner goes. So what is everyones decision. 1967 L-88????

And trucks

[David P.]

Re: AC Oil Cap

This was also used on 67 Impala SS 396-325HP cars.
The 67 396 Impalas had orange painted valve covers, thus the black breather.
I believe 67 Camaros and Chevelles had chrome valve covers and a chrome version of the breather.

DAP

[Joe L.]

Re: AC Oil Cap

This was also used on 67 Impala SS 396-325HP cars.
The 67 396 Impalas had orange painted valve covers, thus the black breather.
I believe 67 Camaros and Chevelles had chrome valve covers and a chrome version of the breather.

DAP

David-----


Those applications help. The part number is GM #6421868. The chrome version was GM #6423033. The 6421868 was discontinued without supercession in September, 1989. The 6423033 was discontinued in February, 1979.

Although it was never cataloged for the 1967 Corvette L-88 application, I expect that this is the SERVICE part number for the breather cap used for that application, too.

[Ronald L.]

Re: AC Oil Cap

David, THanks for posting, yes that's what I recall for the chrome version, limited time period for Chevelle & Camaro.

[Wayne M.]

Re: AC Oil Cap

This was also used on 67 Impala SS 396-325HP cars.
The 67 396 Impalas had orange painted valve covers, thus the black breather.
I believe 67 Camaros and Chevelles had chrome valve covers and a chrome version of the breather.

DAP

Here's what was on my 396 when I picked it up in 1989. When doing a previous owner search in east Texas, the owner in 1970 said he installed the chrome ones, and had the original (orange) covers stored in his father's barn, so I bought them. One of the boxes containing the originals was from Nickey (backwards K) Chevrolet, Chicago, who I believe had a mail order business for hi-po GM parts. One box with the GM sticker indicated # 3925574, which my P&A 30B catalog says is the right hand cover for '67 Sp. H/Per and '68-69 427's. You can see the AC chrome breather; one in each valve cover .

I remember I sold both covers real quick at Bloomington; must have included the breathers 'cause the only one I have now has no AC emboss, so must be aftermarket.