Comparing original vs. repro 63-65 327 oil caps

[David L.]

Has anyone ever compared an original 63-65 327 chrome oil cap with a reproduction cap?

Pictured below are photos of a NOS 3714895 black phosphate oil cap, a NOS 3828373 chrome oil cap, and what I believe is a reproduction 63-65 Corvette 327 cap. I bought these caps at swap meets years ago. The shape of the large "dimple" (about 3/4" to 1" in size) is very "crisp" on the 3714895 and 3828373 caps. The "dimple" on the chrome reproduction cap is quite "vague". The chrome on the reproduction also appears to be "too perfect". The reproduction cap also has a solid gasket (1 11/16" dia.). The NOS caps have a donut shaped gasket (1 1/16" I.D. and 1 11/16" O.D.) which according to the parts catalogs is GM # 3723688.

[Ronald L.]

Re: Comparing original vs. repro 63-65 327 oil caps

David, good observations, the too perfect chrome and washed out appearance go hand in hand, its called over polishing and metal is lost to get the smoother surface.

[Stuart F.]

Re: Comparing original vs. repro 63-65 327 oil caps

I also have one of each in my stock, but never placed them side by side to check for a difference. My original is not as pretty, but should demonstrate the differences you noticed. I will check today and repost my findings.

Stu Fox

[Stuart F.]

Re: Comparing original vs. repro 63-65 327 oil caps

Checked my caps and mine concur with yours. I do have one piece "disc" type gaskets in each, but then I may have changed them at some time over the years. I never intended to have a black phosphate cap, was just sent to me by mistake. My repro cap is on the car because it looks better than my original, chrome wise. The difference in the hump are there, but barely noticeable.

Stu Fox

[David L.]

Re: Comparing original vs. repro 63-65 327 oil caps

Stuart,

I believe that the NOS caps made in the 1980's have a full disc gasket instead of the donut type gasket.

To see the difference between an original cap and repro cap you need to have them side by side or have a photographic memory.

Dave

[Stuart F.]

Re: Comparing original vs. repro 63-65 327 oil caps

Dave;

My report was based on an observation duplicating yours. I even uncovered my car to remove the cap and place it side by side with the orginal cap and the black one. My two chrome caps are very nearly identical, but then my repro was purchased back in the late 70's or early 80's. Perhaps, therefore, it is of NOS then. I had to change out my filler tube then as the connection elbow to the air cleaner had spun out of it's rolled seat in the filler tube. Actually, I think I had to change out that tube at least twice that I recall. A word of caution to anyone else doing that; I used a pull hammer to extract the tube and a regular hammer and wood block to install the new one. One should not over do the installation otherwise you can crack the manifold in the process - seen it done.

Stu Fox

[David L.]

Re: Comparing original vs. repro 63-65 327 oil caps

Stu,

If you bought your chrome cap in the late 1970's or early 1980's it was probably a NOS cap. I'm sure the vendors that sold Corvette parts at the swap meets in the early 1980's still were selling the NOS 3828373 chrome caps. I don't think that the repro caps appeared until the very late 1980's.

GM # 3828373 (chrome cap) sold for $2.00 in Jan. 1978 and sometime between then and December 1981 it was discontinued and replaced by GM # 3714893 (black phosphate cap). I do not have the exact month & year. Obviously you could convert a 3714893 cap to a 3828373 cap by having in chromed.

In my very first post on March 21st GM # 3714895 is wrong, it should be GM # 3714893.

Dave

[Ronald L.]

Re: Comparing original vs. repro 63-65 327 oil caps

One day, long into the future, an archologist will be able to tell us.

There is a land fill in Flint, where they were scrapping out parts deemed to be discontinued. So, we'd only need to dig back wards through those layers. Radios, crate motors, nuts and bolts, and more...

p.s. those parts were what was going there prior to 1980

[William C.]

Re: Comparing original vs. repro 63-65 327 oil caps

Also take a look at the corners, the originals are very crude in the corners as compared to the Reproductions.

[Doug L.]

Re: Comparing original vs. repro 63-65 327 oil caps

The cap on my engine was original. It had to be because it was soo crappy looking and because John DeGregory told me it was when he received it with my FI unit. I had it replated and it came out very nice. I don't have a repro to compare it with but in the attached photo the dimple is very evident. I was under the impression that some repro don't have the dimple.
Doug

[Wayne M.]

Re: Comparing original vs. repro 63-65 327 oil caps

Isn't one of the other indicators of a GM service cap (which I think this one is, about 1980) the stretch marks on the long sides, and the notch in the metal at the corner lips where your thumb would be when tightening or removing ?

[David L.]

Re: Comparing original vs. repro 63-65 327 oil caps

My NOS cap (late 70's, I assume) does have very noticeable "stretch" marks on the long sides but does not really have the "notches" in each of the 4 corners.
The "stretch" marks on the repro cap are very light because of the thicker chrome, I assume.

My NOS 3714893 black phosphate caps have very noticeable "stretch" marks and a very small "V" notch in each of the 4 corners.

[Stan E.]

Re: Comparing original vs. repro 63-65 327 oil caps

I Had A Correct Black Cap Plated And Then Sand Blasted It.

[David L.]

Re: Comparing original vs. repro 63-65 327 oil caps

I Had A Correct Black Cap Plated And Then Sand Blasted It.

Stan,
I assume you sand blasted the black phosphate cap first and then had it chrome plated. The only difference between the 3714893 cap and the 3828373 cap is the type of plating.
It's always better to have original GM parts.
Dave

[Alan D.]

Re: Comparing original vs. repro 63-65 327 oil caps

Here are a couple of originals!
Oh if you leave your car take cap with you, they grow legs.