1969 Engine Block? Need Help! - NCRS Discussion Boards

1969 Engine Block? Need Help!

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  • Jon H.
    Very Frequent User
    • January 1, 1999
    • 147

    1969 Engine Block? Need Help!

    I purchased my 1969 corvette from the 2nd owner who purchased it from the first. The first owner had it until 96. It was a survivor quality car with original everything. He performed a frame off restoration on it and due to finances he sold it to me recently. It is fully option with 300 hp, ac, side exh, pw, etc. It is tuxedo black with ZQ4 interior with all original paperwork. Sounds normal, however when I got into the car I noticed that the casting on the block is 3959512. The pad has the right number and everything matched the pop and the original inspection sheet and a local department of revenue doc with the engine info on it. I spoke to the original owner who swears that the engine, trans and rear end had never been out of the car when he sold it. He wrote me a letter confirming this. He said that he ordered the car with a L46 engine and an automatic. Then he received a call from the salesperson that they were on strike and he would have to wait. 2 mos before the expected delivery he received a call from the salesperson again stating that he could not order the car with an automatic and the L46 option and had to order a bb or a 300 hp with the automatic. He went back forth. Changed the order to a bb then back to a 300hp. It has a correct dated bb rear end, and rear sway bar. It had the original bb half shafts but durring the restoration he put the correct ones on for a sb car.

    I looked up the casting on the internet and it matched up with a 62-63 327 200 hp. However the casing date is I27 68. I panicked and wondered how did this engine get in this car! Then I found this on a site:

    3959512

    This engine casting number is erroneously displayed on many Internet sites as a 1962-63 327-250 hp engine. This is a SERVICE block only. It was available beginning in 1969 as a replacement block, short block, fitted block, and apparently full engine due to some having the engine code stamped on the pad. It is a small journal block used to service 1962 to 1967 applications. It was never used in production of any car as the small journal production car use ended in 1967, two years before this block appeared

    I fully believe that this is the original motor. I also know that the rear end is a correct 3:08 posi as ordered new , however it is a BB code AV. It is dated July 1969. I know it was built after the strike. The build date is M12. Like I said I have a full binder of original paperwork for the car and I seriously doubt anyone would re-stamp a 300 HP car. I know a lot of weird things happened from the plant. I have had a number of factory deviation cars in my collection. Any insight would be greatly helpful. I might have it judged if I can clear this up. As always thanks for your wisdom and your guidance.
  • Tom D.
    Extremely Frequent Poster
    • September 30, 1981
    • 2132

    #2
    3959512 not listed in Colvin's book for 65-69 Chev *NM*

    https://MichiganNCRS.org
    Michigan Chapter
    Tom Dingman

    Comment

    • Steven C.
      Expired
      • October 23, 2006
      • 186

      #3
      Re: 1969 Engine Block? Need Help!

      Some of this sounds a little too weird. If you have the POP, it will have the differential code on it, a '68 date is too early.

      Likewise, the POP will have the engine stampings, what are they? As well as the transmission data plate details, what are they (CK?).

      I'm also confused when you say..."survivor" "frame-off" "engine/trans/rear end never out of car", these terms are typically contradictory.

      Also, highly unlikely that (any) block cast in 1968 would be the original engine in a July built car.

      I know a little about this, my '69 engine was cast and built in March '69, but the car wasn't built until just after the strike (June '69). Mine is a 435hp automatic.

      How about the tune-up/emission label code? POP carb code?

      Steve

      Comment

      • Terry M.
        Beyond Control Poster
        • September 30, 1980
        • 15589

        #4
        Differential help

        "I also know that the rear end is a correct 3:08 posi as ordered new , however it is a BB code AV."

        Contrary to many publications, even including some NCRS publications, there is no such thing as a BB (assume you mean big block) differential. Chevrolet lists some codes as HD. Some, maybe most, authors tend to make this into a big block application -- it isn't. It also applies to automatic transmissions.

        This error has been perpetuated by those folks who like to find small block cars which have grown into big blocks, they use the differential construction as one indicator of this phenomenon. So the myth of "big block" differentials has carried on. It certainly sounds more glamorous, and less a mouthful, than BB & M40 differential.

        BTW: Don't misunderstand me. I am not being critical of your terminology. Just trying to point out how this Myth has been carried on. I don't have my resource library with me, so I can not comment on any of the codes you have presented -- just the differential nomenclature. Thanks for presenting the whole story. It is refreshing to see a post that contains so much information on the opening.
        Terry

        Comment

        • Jim T.
          Expired
          • March 1, 1993
          • 5351

          #5
          Re: 1969 Engine Block? Need Help!

          Jonathan I can comment only on what the previous owner did to make it a small block car by changing the bb half shafts. My original owner 70 Corvette with turbo 400, 3:08 (all 70's had posi-tract, standard equip first year), and 350/300. It came from the factory with caps to attach the half shafts. Some would say 70 small blocks did not come this way from the factory. I know my 70 came from the factory with caps. My POP and stamping on the rear end have CAV. According to the NCRS Specifications Guide, it shows the CAV for 1970 to be a 3:08 Standard for 454. I don't have the 454 for sure. I saw somewhere where in the stuff I have that the CAV was listed as a Heavy Duty rear end. I do know one other thing, my 350/300 with the turbo 400 and 3:08 has chirped the tires more than once in its lifetime shifting from 1st to second. .Perhaps there are other 69's that came from the factory with tubo 400's, base engine, and caps for the rear half shafts.

          Comment

          • Terry M.
            Beyond Control Poster
            • September 30, 1980
            • 15589

            #6
            Re: 1969 Engine Block? Need Help!

            There were plenty of small blocks with the caps on the differential -- all those with the automatic transmission. That was the point of my earlier post. -- Oh and all LT1s also came with caps on the differential. In fact if one did the math -- figure all the Mark IV motors, the small blocks with M40, and the LT1s I think one would find the standard differential was the "rare" item in 1970.
            Terry

            Comment

            • Joe L.
              Beyond Control Poster
              • February 1, 1988
              • 43203

              #7
              Re: 1969 Engine Block? Need Help!

              Jonathan-----

              As far as the block goes, the information that you found on the internet regarding the 3959512 block is correct. Most important, though, is the fact that the 3959512 was a small journal, 327 block. For PRODUCTION purposes, I can see no way that GM could have made this block into a 350 cid engine. And, I can see no way that GM would have originally installed a 327 cid engine in any 1969 Corvette.

              Let's see a good photo of what the stamp pad on this engine looks like.
              In Appreciation of John Hinckley

              Comment

              • Jon H.
                Very Frequent User
                • January 1, 1999
                • 147

                #8
                Re: 1969 Engine Block? Need Help!

                When I said bb rear end I meant big block. And just to clarify it was in a survivor quality condition when the 2nd owner bought it. ie unrestored and the 2nd owner performed a complete frame off restoration. The stamp pad is painted and I will try and clean it off over the weekend. Here are the codes from the protecto plate
                CK69-5159
                AV0731W
                VO725HZ
                C
                8

                The rear end code is a Big Block 3:08 ratio with appropriate sway bar. Also why would someone spend 26K in parts alone to restore a car and resamp the right numbers into an incorrect block. The 3959512 Block was a 2 bolt 327 bloock until 69 when it was a 350 4 bolt main block offered as a warranty (CE) block. It is definitely a 68 cast date block and is a 4 bolt main 350.

                Comment

                • Joe L.
                  Beyond Control Poster
                  • February 1, 1988
                  • 43203

                  #9
                  Re: 1969 Engine Block? Need Help!

                  Jonathan------

                  You mention "the rear end code is a Big Block with appropriate sway bar".

                  No 1969 Corvette small block was originally equipped with a rear sway bar. So, if the car has a rear sway bar, it's either been added or the car was originally a big block (which is not what the P-O-P indicates). Regardless of whether a "big block" differential carrier was installed, the sway bar absolutely would not have "gone with it".

                  As far as the "AV" code being a "big block" code, I believe there is some misinformation in various publications. The "AV" code was used for big blocks with 3.08 ratio, positraction, AND THM-400. Big blocks with 3.08 ratio, positraction, and 4 speed trans used units coded "AW". So, what's the difference between the "AV" and the "AW"? The difference is the PINION FLANGE. For 1968, 1969 and 1970, Corvettes with manual trans used a different pinion flange than those with THM-400. So, there had to be differently coded differential units for each. Both the "AV" and "AW" used cap-type yoke axles.

                  Now, for small blocks with 3.08 ratio, positraction, and manual trans, the rear differential unit was coded "AL". This unit used the manual trans pinion flange and had u-bolt type yoke axles.

                  So, what differential unit was used for small blocks with positraction and THM-400? There were no other 3.08:1 differential unit codes other than the 3 described above used for 1969. Well, since we know that the unit used for 1969 Corvettes with small block, 3.08:1 rear ratio, and THM-400 could not have been the "AW" or the "AL" because they had the wrong pinion flange, the only unit that could possibly have been used for these applications is the "AV". And, that's exactly what you have. Rather than being listed as a "big block" rear axle, it should be shown as ALL 1969 with 3.08:1 ratio AND THM-400.

                  As far as the block goes, I have no information, whatsoever, that the 3959512 was EVER used for any large journal 350 cid engines. Theoretically, the only 350 cid engine that it would have been suitable for was the 1967 Camaro and it's possible that it was used as a SERVICE replacement engine for that application.

                  I think that the engine stamp pad will be very interesting when you are able to post a photo of it.
                  In Appreciation of John Hinckley

                  Comment

                  • Jon H.
                    Very Frequent User
                    • January 1, 1999
                    • 147

                    #10
                    Re: 1969 Engine Block? Need Help!

                    Joe
                    Thanks for the valuable information. I am cleaning off the pad ( it was painted} and I will post a pic tonight if I can.

                    Comment

                    • Jon H.
                      Very Frequent User
                      • January 1, 1999
                      • 147

                      #11
                      Re: Stamp pad pic

                      I cleaned the paint off and this is what I have. The pad looks aged with broach marks. I tried to get the best pic possible. It is still more shinny in the pic.Let me know your thoughts. Thanks for all your help.




                      Comment

                      • Jon H.
                        Very Frequent User
                        • January 1, 1999
                        • 147

                        #12
                        Re: Stamp pad pic

                        Here is the link to the picture






                        Comment

                        • Joe L.
                          Beyond Control Poster
                          • February 1, 1988
                          • 43203

                          #13
                          Re: Stamp pad pic

                          Jonathan------

                          The link did not work because it requires log-in. If you e-mail me the photo, I'll post it for you. I'll send you my e-mail address via e-mail.
                          In Appreciation of John Hinckley

                          Comment

                          • Joe L.
                            Beyond Control Poster
                            • February 1, 1988
                            • 43203

                            #14
                            Jonathan's Stamp Pad Photo

                            Here's the photo I got from Jonathan:




                            http://www.villagephotos.com/viewpubimage.asp?id_=
                            In Appreciation of John Hinckley

                            Comment

                            • Joe L.
                              Beyond Control Poster
                              • February 1, 1988
                              • 43203

                              #15
                              Additional Photos of Jonathan's Block

                              Here are some additional photos of the engine pad and casting numbers.

                              This pad looks to be 100% original to me.




                              Attached Files
                              In Appreciation of John Hinckley

                              Comment

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