Question on '70 LS5 block, restamped at factory???? - NCRS Discussion Boards

Question on '70 LS5 block, restamped at factory????

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  • Norris W.
    Very Frequent User
    • November 30, 1982
    • 683

    Question on '70 LS5 block, restamped at factory????

    I've got a '70 LS5 M21 convertible that I've owned for probably 25 years. At the time I bought it, the seller who was not a Corvette expert represented it as having THE original engine, which I did not believe at the time that it was. Sooooooo, in the way I typically did things in the late 80's/early 90's I found a 512 block that was dated dead right for the car and stamped and stuck it in. The 512 block that was in the car at time of purchase had the pad ground across in a way that would have been typical with a disc sander with the head still installed, but the stamping looked very correct to me at the time. The block was also early for the car by about 6 months or more if I remember. So a year or so later I was talking with a noted Corvette authority at an NCRS meet (I won't name him since I don't recall exactly the specifics of the conversation, but suffice it to say he's written a book or 2 or Corvette restoration). Anyway, in the course of the conversation he said something along the lines of, if there was an issue with an engine, they wouldn't shut the line down to fix it, they'd simply pull another engine and stamp it for the car and away it'd go. He said it was possible that something like this happened and the engine was later fixed if it was minor and stamped for another vehicle. Again, I don't remember much except the gist of the conversation, and it seems odd that if something like this happened they would take the time to also stamp an assembly code on the refinished pad along with the VIN number sequence. The reason this comes up now is that someone has called me and is interested in buying the car. It is presently complete and detailed as it should be with the replacement engine, which I have disclosed to him fully. I've also offered him the engine that was in the car and represented as original at the time I bought it with description on the early dates, the incorrect grinding on pad, etc, etc. To further complicate it, owner 1 & 2 were local here, and 3 & 4 were in Savannah, 160 miles away. 1 was just a kid with a toy and not a collector, 2 was a long time NCRS member and 3 was NCRS member also, although probably not nearly to the caliber that 2 is. Everyone in this chain feels the car had the orginal engine when it passed through their hands and 3 made notes on all the date codes and stampings, which match the engine I pulled. 4 was just a used car dealer who bought it for his wife and wasn't Corvette knowledgeable at all. As far as I'm concerned it's a documented and undamaged LS5 factory air 4 speed convertible with a replacement engine which I installed.

    I'd like opinions on the possibility of an engine pad being ground and re stamped at the factory for whatever reason. I've always been a little skeptical, but the ownership chain seems to suggest it as a possibility also.
  • Patrick H.
    Beyond Control Poster
    • November 30, 1989
    • 11616

    #2
    Re: Question on '70 LS5 block, restamped at factory????

    I'd consider contacting Al Grenning and get his opinion on the pad from the engine you removed.
    Vice-Chairman (West), Michigan Chapter NCRS
    71 "deer modified" coupe
    72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
    2008 coupe
    Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.

    Comment

    • Mark E.
      Extremely Frequent Poster
      • March 31, 1993
      • 4503

      #3
      Re: Question on '70 LS5 block, restamped at factory????

      My 1970 LS5 also has a seemingly original engine that's dated more than six month prior to the car assembly date.

      See Can this 1970 LS-5 block casting date be original to the car?
      Mark Edmondson
      Dallas, Texas
      Texas Chapter

      1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
      1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

      Comment

      • Norris W.
        Very Frequent User
        • November 30, 1982
        • 683

        #4
        Re: Question on '70 LS5 block, restamped at factory????

        Mark, my concern is not only the date code vs assembly date, but primarily the fact that the block has obviously been ground across the pad, seemingly with the cylinder head in place. When I'm back near the block I'll shoot a picture and post it.

        Comment

        • Loren L.
          Extremely Frequent Poster
          • April 30, 1976
          • 4104

          #5
          Re: Question on '70 LS5 block, restamped at factory????

          Assuming you have it reasonably and rationally price, did either of your 2 experts attempt to buy the car back? No? Then there
          lips are making sounds not backed up by their checkbooks. It is ALWAYS going to be a hard story to sell.

          Comment

          • Norris W.
            Very Frequent User
            • November 30, 1982
            • 683

            #6
            Re: Question on '70 LS5 block, restamped at factory????

            Originally posted by Loren Lundberg (912)
            Assuming you have it reasonably and rationally price, did either of your 2 experts attempt to buy the car back? No? Then there
            lips are making sounds not backed up by their checkbooks. It is ALWAYS going to be a hard story to sell.
            I guess I'm missing your point. I contacted all the previous owners many years ago. No, none of the attempted to buy the car back, but I made it clear that I didn't intend to sell it, which I haven't attempted to do now, although I was contacted out of the clear blue by someone looking for one. I'm not really trying to sell any stories and probably won't even sell the car, however I'll still remain interested in the possibility that it could be true, or any other abnormalities in assembly line sequence for that matter. The two guys in the ownership chain who I listed as NCRS members were not what I'd consider experts, however would probably be more knowledgeable than a kid with a new toy or a used car salesman who the other two were.

            Comment

            • Mark E.
              Extremely Frequent Poster
              • March 31, 1993
              • 4503

              #7
              Re: Question on '70 LS5 block, restamped at factory????

              Originally posted by Norris Wallace (6139)
              Mark, my concern is not only the date code vs assembly date, but primarily the fact that the block has obviously been ground across the pad, seemingly with the cylinder head in place. When I'm back near the block I'll shoot a picture and post it.
              Read through the thread again- it has some good information about the engine rework process between St. Louis and Tonawanda. <br>

              This process explains how it may be possible that the manual grind marks you see were done in Tonawanda.<br>

              I'm not saying they were, just that it's possible.
              Last edited by Mark E.; June 12, 2015, 09:37 AM.
              Mark Edmondson
              Dallas, Texas
              Texas Chapter

              1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
              1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

              Comment

              • Norris W.
                Very Frequent User
                • November 30, 1982
                • 683

                #8
                Re: Question on '70 LS5 block, restamped at factory????

                Thanks Mark. Actually I missed the link in your previous post. I'll read it now.

                Comment

                • Kenneth B.
                  Extremely Frequent Poster
                  • August 31, 1984
                  • 2087

                  #9
                  Re: Question on '70 LS5 block, restamped at factory????

                  Originally posted by Mark Edmondson (22468)
                  My 1970 LS5 also has a seemingly original engine that's dated more than six month prior to the car assembly date.

                  See Can this 1970 LS-5 block casting date be original to the car?
                  my 70 454 block was cast Dec.69 & assembled 3/12/70 VIN # 7601
                  65 350 TI CONV 67 J56 435 CONV,67,390/AIR CONV,70 454/air CONV,
                  What A MAN WON'T SPEND TO GIVE HIS ASS A RIDE

                  Comment

                  • Norris W.
                    Very Frequent User
                    • November 30, 1982
                    • 683

                    #10
                    Re: Question on '70 LS5 block, restamped at factory????

                    Mark, I just read through that other discussion. Some great information there. I'm going to try and get pictures first of the week of the pad & casting date and post 'em.

                    Incidentally, I've got an LS6 Chevelle that I've owned since 1981 that's got some funky stuff on the pad, and I'm absolutely positive of the originality of the engine. The first owner was a friend, who wasn't a car guy and swears the engine was never out of the car. All of the date codes and casting numbers are just as they should be for the car, BUT.......... instead of the VIN sequence it's got an A and the last three digits of the VIN. I shot digital pictures of it several years ago and sent it to a nationally known Chevelle judge and he noticed the ghost of the original VIN in the pictures and speculated that it was somehow stamped too lightly for somebody's standards and the assembly line people (Atlanta which would account for the A) stuck that 4 digit code on it rather than slowing the line. He felt 100% that it was original to the car, which I was sure of from the ownership history. I guess back then the priority was keeping the line moving rather than creating images that we'd consider correct and original 45 years later.

                    Comment

                    • Patrick B.
                      Expired
                      • October 31, 2000
                      • 5

                      #11
                      Re: Question on '70 LS5 block, restamped at factory????

                      My 70 too has issues on the pad and was told the same story about restamps and issues on the line. From my engine re-machining experience in the 70's, the first 454's did have some issues as is the case with all first year motors so it's plausible. Not sure about probable. Mine is stamped correctly, my intake is correct, my carb is correct - but the date code on the block is earlier - like 7 months or so in late 69. But I figured I wasn't getting any closer to original than what I had so I went with it.....

                      Comment

                      • Jimmy B.
                        Expired
                        • July 31, 1980
                        • 584

                        #12
                        Re: Question on '70 LS5 block, restamped at factory????

                        69 was a strike year so that may have attributed to time lag

                        Comment

                        • Rich G.
                          Extremely Frequent Poster
                          • August 31, 2002
                          • 1397

                          #13
                          Re: Question on '70 LS5 block, restamped at factory????

                          This post from a while back has a grind out on a stamp pad. 1968 L71. All we know is that it COULD have been done at the factory. Looks like others I have seen. No way to be sure.

                          1966 L79 Convertible. Milano Maroon
                          1968 L71 Coupe. Rally Red (Sold 6/21)
                          1963 Corvair Monza Convertible

                          Comment

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