C3 Distributer Orientation and Tach Cable - NCRS Discussion Boards

C3 Distributer Orientation and Tach Cable

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  • Mike Masters

    C3 Distributer Orientation and Tach Cable

    My 72 coupe (base motor) came with the distributer oriented so that the tach cable connection was facing the firewall with about 2 inches of clearance. (Distributer band has the correct part no. and date code.) The previous owner had tried to connect the tach cable, and because of the sharp 90 degree turn out of the distributer, the cable broke. I too bought a cable, installed it, and forced it to bend sharply when exiting the distributer. The cable was jammed against the firewall, but the tach seemed to work. I took the car out on the street and found that the tach needle would not go above 1500 RPM. After about three minutes of driving the cable broke.

    I bought a cable repair kit, and I turned the distributer clockwise one cylinder, and I moved all of the plug wires around to compensate. The tach connection now points at the drivers side seat, but the vacuum advance connection points towards the passenger seat, and it is jammed up agains the plug wire shield bracket. (I could not turn the distributer two cylinders which would have been better for the tach cable because the vac advance unit would hit the firewall.) I repaired the cable and reconnected. The cable still had to snake in an "S" pattern out of the distributer, around the back of the shielding bracket, and into the firewall. When I started the motor I again found that the tach needle would not go above 1500 RPM. I immediately disconnected the cable to avoid another breakage. Questions: What is the correct position of the distributer? Could something else be broken that would prevent the tach needle from going over 1500 RPM? Thanks.
  • William C.
    NCRS Past President
    • May 31, 1975
    • 6037

    #2
    Re: C3 Distributer Orientation and Tach Cable

    I believe that on a '72 the AIM calls for installation with the vacuum advance tip pointing toward the pass fender, rather than toward the front corner of the car as is the practice in the 67 and earlier cars. Check out the AIM and I believe you will see where you need to be.
    Bill Clupper #618

    Comment

    • Harmon C.
      Extremely Frequent Poster
      • August 31, 1994
      • 3228

      #3
      Re: C3 Distributer Orientation and Tach Cable

      The location of #1 plug wire needs to be in the Corvette position and is one different than other GM cars in some manuals. With this done I would check to see if the distributer is installed on the correct tooth as per any service manual. With everything located right you should be ok but I would inspect and lube the tack drive gears. Lyle
      Lyle

      Comment

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

        #4
        Re: C3 Distributer Orientation and Tach Cable *TL*

        Mike,
        As Bill and Lyle state the C3 position is different than the C2 position. Years ago John Amgwert printed a 1968 Chevrolet Service News bulletin in The Restorer that showed the differences. I have been unable to find it in my Restorer collection, and it didn't make the cut for the CD version of The Restorers. I guess I'll have to go back to the CSN and reprint it.




        Terry

        Comment

        • Mike Masters

          #5
          Re: C3 Distributer Orientation and Tach Cable

          Thanks Bill. Per your note I checked the AIM, and it looks like I have the distributer in the right position. Now I just have to figure out why the tach won't go above 1500 RPM. I suppose it is possible that i put just enough of a kink in the tach cable outer portion to cause some drag on the inner cable, but my obserations don't relly bear this out. I think I'll lube the heck out of the thing and give it another try.

          Comment

          • Michael W.
            Expired
            • April 1, 1997
            • 4290

            #6
            Re: C3 Distributer Orientation and Tach Cable

            Sounds like you have a problem with the gauge, not the cable. If one end of the cable is going a certain speed, the other end has to follow!

            Comment

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