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C2 Ballast Resistor

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  • Richard S.
    Very Frequent User
    • April 1, 2003
    • 288

    C2 Ballast Resistor

    I am looking for information on the ballast resistor for my 63 340 HP car. Appreciate any information on the nominal resistance and any supplier that provides such a part. Coil on the car is an 091. Stock point system.
    Thanks
    Rich
  • Harry S.
    Extremely Frequent Poster
    • July 31, 2002
    • 5293

    #2
    Re: C2 Ballast Resistor

    Originally posted by Richard Sheridan (39583)
    I am looking for information on the ballast resistor for my 63 340 HP car. Appreciate any information on the nominal resistance and any supplier that provides such a part. Coil on the car is an 091. Stock point system.
    Thanks
    Rich
    Rich, I suggest you look for an original (NOS) resistor with the Black dot for SHP as opposed to the blue line for the 250/300 hp cars.

    Think it's part number 1931385
    Last edited by Harry S.; February 16, 2022, 05:27 PM.


    Comment

    • Harry S.
      Extremely Frequent Poster
      • July 31, 2002
      • 5293

      #3
      Re: C2 Ballast Resistor

      Found this, from John.............

      You can follow the usage trail through the Assembly Manual and NPC's (Notice of Production Change) - it goes like this:

      '56 - Early '63 all used the #1931385 (0.3 ohm) resistor; carbureted cars used the #1115091 coil.

      TSB #DR-577 (2/27/63) described the February 4, 1963 production change at St. Louis to the new #1957154 (1.8 ohm) resistor on all 250hp and 300hp engines, " to eliminate point burning during cold-weather operation". The #1115091 coil continued on all points applications. It also noted that the Service parts would be identified with a black dot (for the old 0.3 ohm resistor) and with a blue stripe (for the new 1.8 ohm resistor).

      The #1957154 (1.8 ohm) resistor continued to be released for 250hp and 300hp engines for 1964 start of production, with a new coil (#1115087).

      NPC 307 and 328 released the #1957154 (1.8 ohm) resistor on 1/3/64 for L-76 (365hp) and L-84 (375hp) engines, replacing the #1931385 (0.3 ohm) resistor, along with the #1115087 coil, replacing the #1115091. For the rest of the '64 model year, all Corvettes with point ignition used the same resistor (#1957154) and the same coil (#1115087).

      For '65 (and through 1967), all Corvettes with point ignition used the 1.8 ohm resistor, but the #1115087 coil was replaced by the #1115202 coil.

      K-66 Transistor Ignition-equipped Corvettes didn't use a ballast resistor; the T.I.harness had a built-in length of special resistance wire instead.

      In '68, the ballast resistor disappeared, and was replaced by a length of woven fabric-covered special resistance wire from the fuse block to the coil that served the same function until 1975, when the HEI ignition system was introduced, powered by a full 12-volt feed circuit.


      Comment

      • Richard S.
        Very Frequent User
        • April 1, 2003
        • 288

        #4
        Re: C2 Ballast Resistor

        Harry
        Thank you for the detailed notes. Greatly appreciated.
        Rich

        Comment

        • Robert I.
          Very Frequent User
          • July 31, 2004
          • 164

          #5
          Re: C2 Ballast Resistor

          When did Corvettes stop using ballast resistors? Should I carry a spare with me on my 62 340 hp car?
          ____________________

          Bob Immler

          Comment

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

            #6
            Re: C2 Ballast Resistor

            My 1967 gave me fits recently, the car ran poorly when it warmed up but ran fine when cool. I traced it to a cracked ballast resistor. You can always take the bottom wire and connect it directly to the top wire in a pinch. That was the way I diagnosed the issue. I bought a used one from a friend and it works great.

            Comment

            • Ed S.
              Extremely Frequent Poster
              • August 6, 2014
              • 1377

              #7
              Re: C2 Ballast Resistor

              I purchased 2 ballast resistors for my 64 L76 from "Schafer Classic Reproductions" - Schafer was recommended by someone in another thread some time ago. These resistors are dead on in appearance and functionality. Did an ohm resistance check on both - right dead center of the recommended range. Here is the link to their website. https://shafersclassic.com/c-1164629...ted-parts.html
              Ed

              Comment

              • Richard M.
                Super Moderator
                • August 31, 1988
                • 11323

                #8
                Re: C2 Ballast Resistor

                I always carried a spare ballast in my '59. A Napa version is cheap insurance.

                I also carried points, condenser, VR, belts, lamps, hoses, tools etc.

                Comment

                • Mike M.
                  NCRS Past President
                  • May 31, 1974
                  • 8381

                  #9
                  Re: C2 Ballast Resistor

                  ed; I VIEWED THE BALLAST RESISTORS OFFERED BY SHAFERS. their porcelain portion lacks the cut outs , hence your 64 will get a minor deduct. the cut outs appears in the mid-63 model year corvettes. mike mccagh

                  Comment

                  • Richard S.
                    Very Frequent User
                    • April 1, 2003
                    • 288

                    #10
                    Re: C2 Ballast Resistor

                    Bob
                    Not sure about when ballast resistors stopped being used. But at least to 1967.
                    Rich

                    Comment

                    • Duke W.
                      Beyond Control Poster
                      • January 1, 1993
                      • 15661

                      #11
                      Re: C2 Ballast Resistor

                      A resistance wire in the harness replaced the external ballast resistor beginning in 1968.

                      Failure of the ballast is rare, so I don't see a need to carry a spare, but models with the 0.3 ohm ballast could burn points, especially in cold weather. It happened to my SWC once back in the sixties. Chevrolet wrote a TSB on the issue.

                      A functioning set of points that you replace due to mileage makes a good spare. Set the dwell angle to 30 before you remove them and it should be the same, as will be the initial timing, if you have to swap in the spare to get home.

                      Duke
                      Last edited by Duke W.; November 19, 2022, 02:55 PM. Reason: correct 1963 to 1968

                      Comment

                      • Leif A.
                        Extremely Frequent Poster
                        • August 31, 1997
                        • 3625

                        #12
                        Re: C2 Ballast Resistor

                        If memory serves correctly, the '53 - '67 Corvettes used a ballast resistor, the '68 - '74 Corvettes used a resistance wire and the '75 and later Corvettes eliminated the ballast resistor and resistance wire altogether.
                        Leif
                        '67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
                        Top Flight 2017 Lone Star Regional

                        Comment

                        • Richard M.
                          Super Moderator
                          • August 31, 1988
                          • 11323

                          #13
                          Re: C2 Ballast Resistor

                          Originally posted by Mike McCagh (14)
                          ed; I VIEWED THE BALLAST RESISTORS OFFERED BY SHAFERS. their porcelain portion lacks the cut outs , hence your 64 will get a minor deduct. the cut outs appears in the mid-63 model year corvettes. mike mccagh
                          Mike, Do you mean this cutout? (Pencil tip area)

                          These are the 0.3 ohm versions. (missing the metal punchout tab though)
                          Attached Files

                          Comment

                          • Gary B.
                            Extremely Frequent Poster
                            • February 1, 1997
                            • 7018

                            #14
                            67740880-1371-4F52-B098-2613C522F1D1.jpg

                            Comment

                            • Richard M.
                              Super Moderator
                              • August 31, 1988
                              • 11323

                              #15
                              Re: C2 Ballast Resistor

                              Originally posted by Gary Beaupre (28818)
                              [ATTACH=CONFIG]114244[/ATTACH]
                              Yes must be. I remembered the tab, but not the porcelain.

                              Rich

                              Comment

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