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Block Casting Numbers

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  • Cecil L.
    Very Frequent User
    • May 31, 1980
    • 449

    #16
    Re: Block Casting Numbers

    The block that started my research was the block that came in my 58 Corvette which was a CE 283 block casting 3959532. Then I acquired a 67 Nova which was an original 327 4 speed car. Since the L-79 was dropped for 67, the 327 option was the L-30 275 hp. The block that was in the car when I got it was an L-79 shortblock where the original L-30 had been, complete with high compression pistons. It was a real Chevy II block but the casting number was 3959538 and I couldn't find anything on this block either.

    My research turned up a series of service castings which I initally thought were only for small journal service requirements after the SJ was out of production coinciding with the start of the CE warranty replacement program in late 68.

    3959512 327 pass/truck
    3959532 283 pass/truck
    3959534 283 Chevy II
    3050538 327 Chevy II

    I reported my findings with documentation to the Mortec site which resulted in the addition of the 3959538 to the listing of Chevy II blocks.
    '
    Further reaearch turned up examples of the 3959512 4" bore block in both small journal and large journal and with 2 bolt and 4 bolt mains and with cannister or spin on oil filter configuration. The SJ versions had the crankcase vent provision on the back of the block and the LJ had the pad but it was not machined, just like the 68 blocks, The only 4 bolt main versions I saw examples of were as 302 engines in 69 Camaros, and some had original appearing assembly and VIN stamps with broach marks instead of the more typical CE stamp.The only explanation I could imagine other than counterfeit is the possibility that some 3959512 service blocks may have been used in production possibly due to the strike in 69. I'm guessing the service blocks may have been batch poured and stored for machining as necessary for service. It seems possible that some of these could have ended up in 69 Corvettes as 327 or even 350 versions. Has anyone seen that?

    Both of my blocks and an NOS 3959534 Chevy II short block that I have pics of, had casting dates of A_9. All were identical to my 68 Chevelle 678 block (except for the recessed oil filter on the 538 block. All had the long stamp pad and All had CE9 plus the sequential numbers of the CE service blocks so naturally I assumed they were 69 service castings from the CE -5/50 warranty service program. The main difference I have found is that they have the last 3 digits of the casting number on the side of the block like the later one piece seal castings which makes me wonder if they were maybe 79 castings instead of 69, but that would mean they were still casting and selling SJ configured service blocks much later than I thought.
    The earlier CE blocks I've seen did not have the side casting numbers so that is a prt of the puzzle I would like to solve to try to narrow down the casting date range on these oddball castings which so far have little documented history.

    Anyway, that is the quest. I know it has little to nothing to do with actual production Corvette history, unless examples can be found in 69's, but it' still interesting to me.

    Comment

    • John H.
      Beyond Control Poster
      • December 1, 1997
      • 16513

      #17
      Re: Block Casting Numbers

      Cecil -

      Here's a full set of patterns and cores (6 large & 3 small) for the small-block; those (9) pieces enormously simplified casting that block. The previous best GM V-8 casting design practice used (15) patterns and cores. More patterns & cores = more sand joints and fit issues = more core shift variation.


      BlockCores (2).jpg

      Comment

      • Cecil L.
        Very Frequent User
        • May 31, 1980
        • 449

        #18
        Re: Block Casting Numbers

        Thanks John, I've seen that before alongside the 15 part core for comparison.

        Maybe it was a Chevy II thing. Here's a 64 production Chevy II block with the last 4 of the casting number on the side like my 327 so maybe my block is a 69 casting after all.

        Comment

        • Steven B.
          Extremely Frequent Poster
          • June 30, 1982
          • 3986

          #19
          Re: Block Casting Numbers

          Originally posted by Steven Brohard (5759)
          Cecil, I am having a hard time posting picture and will continue to try. My '57 Corvette 245 HP that I bought Nov, 1964 has 548 cast on the side. Having spoken to the previous owners from new it is the original block. It has cast K266 which is in line with the build date of mid-Dec. '56.

          Steve

          Got it!


          To clarify, the picture is of the rear of my original block.

          Comment

          • Cecil L.
            Very Frequent User
            • May 31, 1980
            • 449

            #20
            Re: Block Casting Numbers

            Where is the pic?

            Comment

            • Steven B.
              Extremely Frequent Poster
              • June 30, 1982
              • 3986

              #21
              Re: Block Casting Numbers

              Originally posted by Cecil Loter (3596)
              Where is the pic?
              Another one that shows on my screen and not for others! I will work on it Cecil. Thanks for letting me know. Steve

              Comment

              • Steven B.
                Extremely Frequent Poster
                • June 30, 1982
                • 3986

                #22
                Re: Block Casting Numbers

                Pic of 548 on rear of '57 block. Let me know if you can view it, I can see it.

                1957 548 Block DSC00508.jpg1957 548 Block DSC00508.jpg

                Comment

                • Cecil L.
                  Very Frequent User
                  • May 31, 1980
                  • 449

                  #23
                  Re: Block Casting Numbers

                  Got the pics, but having a hard time visualizing the location on the side of the block. That looks alot like what would be on the front under the timing cover.

                  Comment

                  • Terry M.
                    Beyond Control Poster
                    • September 30, 1980
                    • 15596

                    #24
                    Re: Block Casting Numbers

                    Two of the same shot. Works for me at work.
                    Terry

                    Comment

                    • Steven B.
                      Extremely Frequent Poster
                      • June 30, 1982
                      • 3986

                      #25
                      Re: Block Casting Numbers

                      Cecil, the pic is from the back of the block, hidden by the bell housing.

                      Terry, I got nervous and could not quit hitting the "Insert Inline" selection---



                      Steve

                      Comment

                      • Cecil L.
                        Very Frequent User
                        • May 31, 1980
                        • 449

                        #26
                        Re: Block Casting Numbers

                        OK, that explains it. It's not on the side of the block but on the back. That's the end pattern and they all have the last three digits of the casting number of all blocks using the same pattern in production at the time. Same on the front pattern

                        Comment

                        • Steven B.
                          Extremely Frequent Poster
                          • June 30, 1982
                          • 3986

                          #27
                          Re: Block Casting Numbers

                          Originally posted by Cecil Loter (3596)
                          OK, that explains it. It's not on the side of the block but on the back. That's the end pattern and they all have the last three digits of the casting number of all blocks using the same pattern in production at the time. Same on the front pattern

                          Sorry, I did not pay attention to your post stating on the side. I have some over the counter 283 blocks I will check.

                          Comment

                          • Cecil L.
                            Very Frequent User
                            • May 31, 1980
                            • 449

                            #28
                            Re: Block Casting Numbers

                            So far, the only blocks i have found with the 3 casting number digits on the side are all Chevy II blocks.
                            Beginning with the first Chevy II 283 V8 blocks (cast 194) in 64, then 65, 66, and 67 both 283 (cast 194) and 327 blocks (cast 721 and 362), continuing in the 3959534 and 3959538 Chevy II service blocks cast from late 68 until mid 70 at least.
                            I have looked at numerous examples of the regular SB castings up to and including the 3959512 and 3959532 service blocks and none have the digits on the side.

                            Must be a Chey II thing only.......... Maybe for easier identification on the engine assembly line.

                            Comment

                            • John H.
                              Beyond Control Poster
                              • December 1, 1997
                              • 16513

                              #29
                              Re: Block Casting Numbers

                              Originally posted by Cecil Loter (3596)
                              So far, the only blocks i have found with the 3 casting number digits on the side are all Chevy II blocks.
                              The left side pattern and core were unique to the Chevy II V-8 block due to the vertically-recessed oil filter provision - not used for any other application.

                              Comment

                              • Cecil L.
                                Very Frequent User
                                • May 31, 1980
                                • 449

                                #30
                                Re: Block Casting Numbers

                                Originally posted by John Hinckley (29964)
                                The left side pattern and core were unique to the Chevy II V-8 block due to the vertically-recessed oil filter provision - not used for any other application.
                                Thanks John, I know that but was wondering if including the last 3 of the casting number on the side patterns was a policy or process change applied to all block casting procedures and when it started. Apparently it was only for the recessed filter Chevy II, but why?

                                As far as I can tell, it started showing up on the regular small blocks at least by 83 as I have an 83 Z-28 bock with the numbers on the side.

                                Comment

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