66 427 oil fill cap variations

[Ronald L.]

Did every search and verified what was there before posting...

There seems to be many variants of the S - Stant cap purported to be original for 1966 and or other years:

1. Dimples on the ears or lack therof.
2. Bevel or not much of one to the lower center area.
3. Squared off S or rounded S.
4. Presence of the SMC stamp down in the center area.
5. Size and shape of the back side of the rivit.


What is correct for 1966 427? Is there a definitive cap?

[David S.]

Re: 66 427 oil fill cap variations

Our early 66 (Sept. 65 built) L72 uses the squared oil cap with no point deducts. The squared oil cap is used for 65 L78 (396ci x 425hp) and early 66 L-36 and L72's.

Early - mid production 66 the caps switched to the round S. All of 67 also uses the round S. All original caps from 65/66/67 should have the SMC stamp, dimples of the ears. Also look at the differences in the center rivets.

Your car depending on the build date should use either the first design 65 (squared S) or the 66/67 design round S.

Original 66/67 Cap:





Repro Cap:





-Dave

[Vernon S.]

Re: 66 427 oil fill cap variations

I have an original L-36 with a build date on 11/5/65 and the "S" is squared off. The remainder of the characteristics are as David Schutzbank described.

[Steve B.]

Re: 66 427 oil fill cap variations

I will try to post a pic of a squared original

[Jack H.]

Re: 66 427 oil fill cap variations

Here's a pix of the version of the cap with the squared 'S' emboss...

[Ronald L.]

Re: 66 427 oil fill cap variations

I am dealing with a very late April, looks like the rounded version is preferred from those weighing in, thus far. Is there more than one repro part? Stant says those GM owned tools are long out of their hands.

[David S.]

Re: 66 427 oil fill cap variations

I guess there are more than one repro. However, the "correct" repro's are still different. Also I am yet to see a squared S repro.

If you having your car judged I'd find an original. I have one or two, if your interested PM me.

-Dave

[Steve B.]

Re: 66 427 oil fill cap variations

I was wondering what color is correct for an original cap? I have seen both black and green ones and would like to know which is correct?

[David S.]

Re: 66 427 oil fill cap variations

I think the closest finish to original would either be a black oxide paint or black oxide coating. I prefer it over a semi gloss black. The underside should be natural or zinc plated.

-Dave

[Ronald L.]

Re: 66 427 oil fill cap variations

Agree it is not a normal flat to sg black - do you have a source?

[David S.]

Re: 66 427 oil fill cap variations

As a source for restoration. I either re-plate them or shoot them with Quanta's black oxide paint. I have had great success doing that.

As a source of originals. I have seen numerous caps on unrestored cars. They are not regular black. Maybe someone else will chime in with exact specifics on the proper coating.

-Dave