C-2 Distributor - NCRS Discussion Boards

C-2 Distributor

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  • Don Ursery

    C-2 Distributor

    Can a distributor without vacum-advance be installed on '66 327-300hp? I have a tach-drive dist. without vacum-advance, just wondering the difference.
  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    #2
    Re: C-2 Distributor

    Don------

    Yes, a non-vacuum advance distributor can be installed. For such a distributor, all of the advance has to be provided by the centrifugal (mechanical) advance. In general, vacuum advance is a great asset for a street engine since it will significantly improve fuel economy and other engine operating parameters.

    If a centifugal-only distributor were to be used on your engine, the centrifugal advance characteristics would likely have to be re-calibrated ("re-curved") to provide acceptable operating characteristics for the engine.

    Personally, except for engines originally so-equipped, I would not even consider using a distributor without vacuum advance.
    In Appreciation of John Hinckley

    Comment

    • Duke W.
      Beyond Control Poster
      • January 1, 1993
      • 15610

      #3
      Re: C-2 Distributor

      The engine will run, but it may have poor idle characteristics, tend to run hot or overheat at idle and low speed driving, and have poor fuel economy.

      If it is a Delco single point tach drive distributor, you can install a properly calibrated vacuum advance for the 300 HP engine.

      If it is an aftermarket dist. that will not accept a vacuum advance I would sell or trade it for a Delco single point tach drive dist. and install a proper vacuum advance.

      Duke

      Comment

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

        #4
        Re: C-2 Distributor

        Duke-----

        Most of the non-vacuum advance Delco tach drive distributors that I am familiar with do not have provisions for the installation of a vacuum advance control. The basic housing is the same, but there is no machining on the upper portion of the distributor housing for the vacuum control. I supose such machining could be performed, but it would be simpler just to get a housing already so-machined.

        The only exception that I can think of is the 67-69 L-88/ZL-1 distributors. These TI distributors were centrifugal advance only. However, they did have the machining for the vacuum control and they did have a "vacuum control" installed. This "vacuum control" had no nipple on it for a vacuum line and there was no way to attach such a line. Incredibly, it did have an actuator rod out the rear which was connected to the TI base plate in a normal fashion! The vacuum control even had the customary Delco stamping on it with the last 3 digits of the part number AND the number of degrees advance that it would produce!!!!! But it was a "eunuch"; it could produce no vacuum advance, at all, since it had absolutely NO provisions for a vacuum line. I've NEVER been able to figure that one out and I've thought about it for years.

        That vacuum advance control was GM #1115373 and it was available into the late 80s.
        In Appreciation of John Hinckley

        Comment

        • Duke W.
          Beyond Control Poster
          • January 1, 1993
          • 15610

          #5
          Re: C-2 Distributor

          Joe -

          The only Delco tach drive distributor I can think of that did not have provison for a vacuum advance was the late dual point distributor. All single point tach drive housings that I know of must have a vacuum advance to secure the breaker plate or pickup coil baseplate (TI)from rotating.

          You may remember that I bought the TI system from the orignal owner of the "12 mile L-88" in 1967. As you say, it had a vacuum can, but the nipple was cut off to preclude its use as the L-88 was a racing engine and vacuum advance was not considered, but something had to be there to keep the base plate from rotating, so a vacuum can was installed at Tonawanda with instructions to cut off the nipple. When I installed the system in my '63 L-76 I installed my '64 spec ignition map, which included the "236-16" vacuum can, weights and springs, and saved the original L-88 parts. When I retired the TI in the mid seventies in favor of a my original single point that I had blueprinted, I reinstalled the original modified vacuum can and weights and springs in the L-88 distributor, and that's how it was configured when I sold the system to David Burroughs in '88.

          My Cosworth Vega did not have a vacuum advance from the factory. (It does now.). The pickup coil was secured from rotating by a plastic piece with a mounting pattern equivalent to the vacuum can and a tang to hold the base plate in a fixed radial orientation.

          Duke

          Comment

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

            #6
            Re: C-2 Distributor

            Duke----

            Yes, the 62 1110985 distributor is the only PRODUCTION distributor that I can think of that did not use vacuum advance, but there may have been a few others. However, the GM #1111263 SERVICE-only, ball bearing TI distributor did not have vacuum advance, either. Both the 985 and the 263 used housings that had no provisions for vacuum advance. I don't understand why the L-88 distributor was not set up the same way as the 263.
            In Appreciation of John Hinckley

            Comment

            • Don Ursery

              #7
              Re: C-2 Distributor

              Gentlemen,

              Thanks a ton for your expertise and knowledge. The only reason I considered this is the car came with a "Mallory" tach-drive w/o vac. adv. After hearing your input, I'm going to go with a vac. adv. original. Again, always thankful for members like you.

              Comment

              • Bob Simard

                #8
                C-2 Distributor

                How about the 1110914 distributor used in 1960 on FI cars? Can vacuum advance be added to this distributor or must a later FI distributor be used? Thanks

                Comment

                • Duke W.
                  Beyond Control Poster
                  • January 1, 1993
                  • 15610

                  #9
                  Re: C-2 Distributor

                  FI distributors through '62 were all dual point with no vacuum advance provision. (The 250 and 275 HP 283 FIs with hydraulic lifters MIGHT be an exeption, but my recollection is they used the dual point with different calibration than the Duntov-cammed FI engines, so they carried different part numbers.)
                  All FI distributors tend to be worth a premium because the FI pump drive makes them mandatory for use with FI systems.

                  Cast iron housing tach drive single points were used on most Corvettes from '63 to '74, so they are relatively common, and the ignition advance map is easily tailored to any engine configuration by proper vacuum can and centrifugal advance spring selection.

                  The only FI distributors that will accept a vacuum can are '63 to '65 versions that had a special housing with both a tach and FI drive, but all the ignition related parts were generic Delco single point with the exeption of a special low height cap so everything would fit under the shielding.

                  Duke

                  Duke

                  Comment

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