Indicators of a 1971 Big Block Car - NCRS Discussion Boards

Indicators of a 1971 Big Block Car

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  • Nick P.
    Expired
    • March 15, 2011
    • 13

    Indicators of a 1971 Big Block Car

    My friend is restoring a 71 vette. He purchased it with a crate engine installed. The core support appears original and is for a 454. However, that can easily be replace along with other indicators of engine size such as the console plate, etc. Are there any indicators that are not as easily changed that would provide an indication if the car was originally a small block or big block? I appreciate the help!
  • Patrick B.
    Extremely Frequent Poster
    • August 31, 1985
    • 1995

    #2
    Re: Indicators of a 1971 Big Block Car

    Does it have a rear sway bar? What is the rear end code? What is the diameter of the front sway bar?

    Comment

    • Mark E.
      Extremely Frequent Poster
      • April 1, 1993
      • 4528

      #3
      Re: Indicators of a 1971 Big Block Car

      Aren't big block half shafts shot peened?
      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

      • Ron G.
        Very Frequent User
        • December 1, 1984
        • 865

        #4
        Re: Indicators of a 1971 Big Block Car

        Some indicators are suspension components such as shocks and their tags, front coil springs and their tags, the size of the front swaybar and also if they have rear swaybars. Also look for the heavy duty caps on the inboard part of the axle half shaft connecting to the outboard part of the rear end All big blocks have, automatic big and small block along with small block high-performance and all automatics are shot permed with number 31 number 31 shot. Those are just some indicators.
        "SOLID LIFTERS MATTER"

        Comment

        • Nick P.
          Expired
          • March 15, 2011
          • 13

          #5
          Re: Indicators of a 1971 Big Block Car

          Originally posted by Patrick Boyd (9110)
          Does it have a rear sway bar? What is the rear end code? What is the diameter of the front sway bar?
          The car does not have a rear sway bar and the front is 0.75 inches. It also appears to have original AC...which I understand was not offered with big blocks?

          Comment

          • Tim G.
            Extremely Frequent Poster
            • March 1, 1990
            • 1374

            #6
            Re: Indicators of a 1971 Big Block Car

            AC was not offered with the LS6, but it was available with the LS5.

            Comment

            • Stephen L.
              Extremely Frequent Poster
              • May 31, 1984
              • 3156

              #7
              Re: Indicators of a 1971 Big Block Car

              At some point in this era the engine designation code became part of the Vin..... don't know when that started but it's worth checking out

              Comment

              • Patrick B.
                Extremely Frequent Poster
                • August 31, 1985
                • 1995

                #8
                Re: Indicators of a 1971 Big Block Car

                3/4" front sway bar and no rear sway bar are small block attributes. What is the rear end code?

                Comment

                • Larry M.
                  Expired
                  • December 1, 1986
                  • 541

                  #9
                  Re: Indicators of a 1971 Big Block Car

                  For at least GM, 1972 was the first year that included an engine identifying character in a car's VIN.

                  Comment

                  • Joe L.
                    Beyond Control Poster
                    • February 1, 1988
                    • 43211

                    #10
                    Re: Indicators of a 1971 Big Block Car

                    Originally posted by Stephen Lavigne (7553)
                    At some point in this era the engine designation code became part of the Vin..... don't know when that started but it's worth checking out

                    Stephen------

                    1972 was the first year for the engine coded into the VIN.
                    In Appreciation of John Hinckley

                    Comment

                    • Joe L.
                      Beyond Control Poster
                      • February 1, 1988
                      • 43211

                      #11
                      Re: Indicators of a 1971 Big Block Car

                      Originally posted by Nick Petruzzi (53092)
                      The car does not have a rear sway bar and the front is 0.75 inches. It also appears to have original AC...which I understand was not offered with big blocks?

                      Nick------


                      The car in question is an original small block car. No doubt in my mind about it, at all.
                      In Appreciation of John Hinckley

                      Comment

                      • Ron G.
                        Very Frequent User
                        • December 1, 1984
                        • 865

                        #12
                        "SOLID LIFTERS MATTER"

                        Comment

                        • Patrick B.
                          Extremely Frequent Poster
                          • August 31, 1985
                          • 1995

                          #13
                          Re: Indicators of a 1971 Big Block Car

                          The rear end code indicates whether the heavy duty caps were on the rear from the factory. Also the code would show whether the ratio was typical of a LS -5 or an LT-1.

                          Comment

                          • Ron G.
                            Very Frequent User
                            • December 1, 1984
                            • 865

                            #14
                            "SOLID LIFTERS MATTER"

                            Comment

                            • Mike E.
                              Extremely Frequent Poster
                              • February 28, 1975
                              • 5136

                              #15
                              Re: Indicators of a 1971 Big Block Car

                              In 71, AX was code for heavy duty 3.36, LR for regular 3.36. Why they had the two codes for 3.36 only, I have no idea.

                              Comment

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