Technical Trivia Question - NCRS Discussion Boards

Technical Trivia Question

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  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    Technical Trivia Question

    As most folks know, Chevrolet V-8 engines have had, from their inception in 1955, much parts interchangeability between various model years and engine configurations. This is one of the great strengths of Chevrolet V-8 engines within a generational series. Many of the engine internal parts were used year-after-year in a whole range of engines and especially included items like rocker arms, rocker studs, valve lifters, valve springs, timing set components and many others. Sometimes, part numbers were changed, but the actual parts changed very little, often in virtually non-discernable ways.

    For the purpose of this question, I'm going to focus on timing sets and components thereof. Most folks think that these parts are among the "most standard" of components found within a generational series of engines and, for the most part, they are correct. However, there were changes that most folks might not realize. One interesting fact is that during the entire 1955 to 2007 production period for Chevrolet engines (whether manufactured by the old Chevrolet Division or GM Powertrain) there were only TWO model years that used a timing set (i.e camshaft drive) or component(s) thereof that were UNIQUE to each of those 2 model years. Furthermore, I'm not talking about just a part number change with little change in the actual part; I'm talking about substantive configuration and/or design differences used only for each of the 2 model years. This is a 5 part question and the elements are:

    1) What were the model years?

    2) What were the engines?

    3) What were the specific unique component or components for each of the 2 model years?

    4) What was the configuration of the unique component or components?

    5) What made them unique to that model year?

    By the way, the above question applies to engines installed in passenger cars, including Corvette, and light trucks (10-30 series). It does not apply to MD and HD trucks which used different components and are far beyond the scope of discussion on this board.
    In Appreciation of John Hinckley
  • Clem Z.
    Expired
    • January 1, 2006
    • 9427

    #2
    Re: Technical Trivia Question

    some truck engines use a roller chain and gear drives

    Comment

    • Verle R.
      Extremely Frequent Poster
      • March 1, 1989
      • 1163

      #3
      Re: Technical Trivia Question

      Joe,

      If I remember correctly some big block engines used gear drives, no chain. This required the cam to be ground "backwards" since it turned reverse to normal cam rotation and the cam gear on the distributor to be cut "backwards" so the distributor would turn the normal direction.

      I will guess the years to be 68 and 69 and the engines to be L88s.

      Verle

      Comment

      • Warren F.
        Expired
        • December 1, 1987
        • 1516

        #4
        Re: Technical Trivia Question

        My guess would be '69 ZL-1 and '90 ZR1

        Comment

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

          #5
          Re: Technical Trivia Question

          If we're talking about normal production small-blocks, it might be the Gen II reverse-flow cooling engines (LT1, LT4) where the water pump was driven by a jackshaft off the cam sprocket.

          Comment

          • Terry M.
            Beyond Control Poster
            • September 30, 1980
            • 15573

            #6
            Re: Technical Trivia Question

            I was going to post that one John, but the Gen II LT1 went for more than two years -- 1992-1996 in the Corvette, and then there was the LT4 -- I'm not sure how long that one went for.
            Terry

            Comment

            • Joe L.
              Beyond Control Poster
              • February 1, 1988
              • 43193

              #7
              Re: Technical Trivia Question

              clem-----

              Yes, but I'm excluding MD and HD truck applications for the purpose of this question. Light duty trucks used the same engines and components as passenger cars. Even if I had included them, though, it would not have made any difference. These special timing sets or gear drives used in trucks were not unique to any specific model year---they were used for many years running.
              In Appreciation of John Hinckley

              Comment

              • Joe L.
                Beyond Control Poster
                • February 1, 1988
                • 43193

                #8
                Re: Technical Trivia Question

                Verle----

                All PRODUCTION L-88's built from 1967 through 1969 used a chain drive cam and timing set. The timing set components were not unique to L-88 but were shared with certain other engines. The same components were used for the entire L-88 period.

                Most SERVICE L-88 engines used the chain drive system, too. However, I believe that there were some special SERVICE type engines built which had the gear drive system. Also, the components of the gear drive system were once available in SERVICE for retrofit to any big block.
                In Appreciation of John Hinckley

                Comment

                • Joe L.
                  Beyond Control Poster
                  • February 1, 1988
                  • 43193

                  #9
                  Re: Technical Trivia Question

                  Warren-----

                  1969 ZL-1 used the same timing set as 1967-69 L-88 and the same as used for certain other big block engines. There may have been some SERVICE aluminum big block engine assemblies which included the gear drive timing. However, these were not model year-specific engines and were not the same as any ever used in PRODUCTION.

                  All 1990 to 1995 used, essentially, the same timing set components; there was no year among them that used a unique-to-that-year component.
                  In Appreciation of John Hinckley

                  Comment

                  • Joe L.
                    Beyond Control Poster
                    • February 1, 1988
                    • 43193

                    #10
                    Clarification

                    Based upon some of the responses, I may not have been too clear in part of the question. So, I'll clarify and provide a subtle "hint": the two model years that have a unique-to-that-model year timing set component or components are not consecutive model years and NONE of the components of each of the 2 model years in question are shared by the 2 model years.

                    Also, just to be perfectly clear, we're talking about engines originally installed in passenger cars or light trucks or SERVICE equivalents thereof. I'm not referring to "special engines" available only in SERVICE and which were non model year specific. Also, not referring to "experimental" or "back-door" engines. Obviously, the possible "permutations" which these could have included are "endless".
                    In Appreciation of John Hinckley

                    Comment

                    • Phil P.
                      Expired
                      • April 1, 2006
                      • 409

                      #11
                      Re: Technical Trivia Question

                      are we talking timing set only or anything involved with the valve train--i.e cam gear to valve???---you have us interested !!!!!

                      Comment

                      • Robert S.
                        Very Frequent User
                        • July 31, 2004
                        • 377

                        #12
                        Re: Technical Trivia Question

                        Just a guess...

                        1) What were the model years? 93 & 94

                        2) What were the engines? LT1 & LT4

                        3) What were the specific unique component or components for each of the 2 model years? SOMETHING WITH THE CAM

                        4) What was the configuration of the unique component or components? ????

                        5) What made them unique to that model year? ????
                        Bob

                        Comment

                        • Robert S.
                          Very Frequent User
                          • July 31, 2004
                          • 377

                          #13
                          Re: Technical Trivia Question

                          cORRECTION ON #3

                          3) What were the specific unique component or components for each of the 2 model years? SOMETHING WITH THE CRANK - POSITION INDICATORS?
                          Bob

                          Comment

                          • Joe L.
                            Beyond Control Poster
                            • February 1, 1988
                            • 43193

                            #14
                            Re: Technical Trivia Question

                            PHIL------

                            Just the timing set or components thereof (i.e timing chain, crank sprocket, cam sprocket).
                            In Appreciation of John Hinckley

                            Comment

                            • Verle R.
                              Extremely Frequent Poster
                              • March 1, 1989
                              • 1163

                              #15
                              Re: Technical Trivia Question

                              Bob,

                              I believe the Corvette LT1 ran from 92 through 96 with a change in the pump drive in 95. The LT4 drive was like the LT1.

                              Verle

                              Comment

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