Big Block 66/67 Oil Pan ID

[Peter M.]

I have seen claimed NOS Big Block 66/67 oil pans but understand there are differences form originals ie certain dimples etc. Anyone know how to spot an original as compared to later GM releases or have good pictures to ID one?

[Joe L.]

Re: Big Block 66/67 Oil Pan ID

Peter-----

I've compared the pans, but not in with "excruciating and painstaking" comparison of every square inch of the pan and every nuance of feature. However, I can tell you this: there were 3 big block pans used over the 65-74 PRODUCTION period and one which was/is a SERVICE-only pan.

63-68-----GM #3872429-----has corner reinforcements; hole in front oil pan seal radius for front cover screw; unpainted in SERVICE;

69--------GM #3955106-----has corner reinforcements; may or may not have hole described above; unpainted in SERVICE;

70-74-----GM #3977591-----no corner reinforcements; no hole in front seal radius; supplied in SERVICE with GM #3967854 baffle; may have been supplied in SERVICE as bare metal or painted Chevrolet orange;

post 1987 SERVICE---- GM 14091356-----same as 3977591 except painted or powder-coated black.

Certainly, there may have been slight differences in the pans due to wear of the tooling over the years and this may account for nuances of configuration differences. However, I really think that all of the pans, from the very first one in 1965 to the SERVICE pans available to this very day were produced off of the same tooling. Keep in mind that this is a Corvette-only pan; it was not used for any other chassis application. Corvettes were very limited production cars, only used big blocks for 10 model years, and big blocks in Corvettes during the years that they were available were the exception, not the rule. All this adds up to VERY limited need for Corvette big block oil pans in PRODUCTION and SERVICE.

The die set used to manufacture these pans was undoubtedly a progressive die set with 7 or more stages. All of this equals high cost to manufacture the tooling. I doubt that there ever was more than one set of tooling and I really doubt that it was changed much, if any, over the years. The elimination of the hole in the front radius and the corner reinforcements didn't require much change in the tooling.

[Peter M.]

Re: Big Block 66/67 Oil Pan ID

Joe

Your response was most helpful and I was immediately able to identify one of the NOS pans I have. Thanks much for the detail you provided.

[Joe L.]

Addendum

One thing that I would be interested in confirming is the configuration of the 69-only oil pan, GM #3955106. Of course, there is no way to identify that pan on a car or confirm that part number since part numbers are not stamped on Chevrolet oil pans. However, if someone has a known-original 69 big block (or, even, just one that they're pretty sure is original), I'd be interested in confirming the presence or absence of the corner reinforcements and the presence or absence of the hole in the front seal radius. Both of these are very easy to discern if one can take a glance under the car. In fact, I think that I posted this same query quite some time ago without any responses. Hopefully, this time several of you will be able to provide some input.

Also, two other things that I should have mentioned in my original post:

1) ALL Corvette big block oil pans have the oil drain on the lower rear surface of the pan, offset from center;

2) NO Corvette big block oil pans have the "dimples" on either side of the front section of the pan.

Many full size passenger car and Chevelle oil pans of the 60s-70s period have the side drain and "dimples" on the front section of the pan. These pans were NEVER originally used on a Corvette.

[Bill W.]

Re: Addendum

Joe my 65 BB pan has the reinforcements at the corners,rear drain,hole in the front and no dimples,and has the trapdoor. I have a 69 L89 pan that I bought about 11 years ago from a friend who owned the car and bought a new pan because his had dents we think it was the original? It has all the same things as my 65 pan and in the same places except the hole in the front BUT it has the 2 small dimples on each side of the pan valley ? whats your guess? Bill

[Joe L.]

Re: Addendum

Bill-----

Are the dimples that you're referring to on the sides of the forward section of the pan about half-way between the sump and front pan seal radius? If so, then that must be a feature of the 69-only pan that I was not aware of. I know that the 65-68 pan does not have the dimples, I'm relatively sure that the 70-74 does not, and the 14091356 SERVICE pan does not.

If anyone has a known-original 70-74, I'd be interested in hearing about their observation on this feature. Keep in mind that the dimples that I'm talking about are located as I described above. They are not the "creases" on either side seen in the transition section of the pan from the forward section to the sump.

[Bill W.]

Re: Addendum

Joe no these are in the sump area about 2/3s of the way back .they are 2 vertical 2" long indents about the size of a pencil 2 on each side. other than my 65 pan not having them I never thought about them .the 69 it came off of was a L89 auto, Bill

[Joe L.]

Re: Addendum

Bill------

The indentions that you are referring to are not the "dimples" that I was talking about. The "dimples" that I was referring to are in the forward (shallow) section of the pan about half-way between the sump and the front of the pan. These "dimples" are seen on Chevelle/passenger car pans, but not Corvette pans. I believe that they are a feature which was used to accomodate some Chevelle chassis clearance requirement.

Now, with respect to the 2 vertical "indentions" on each side of the sump that you described, I thought that these were a feature of all Corvette big block pans from 1965 through 74. I would reckon their purpose is to strengthen the pan, however minimally. But, if your 65 pan doesn't have them, then that's a difference that I was not aware of in the 65-68 "edition" of the pan. Perhaps these were added for the 1969 "edition". It seems strange to me that GM would have revised the tooling of the pan just to add these "indentions"; it's hard to imagine that their presence or absence would be significant. I'd love to know the story regarding why they were added, but I'll bet it's lost in antiquity.

Also, it would be interesting to hear from some other 65-68 big block owners with original oil pans regarding this feature. It would be easy to check by a simple glance under the car.

[Bill W.]

Re: Addendum

Thanks Joe