Grounding Coil for Comp Check TI - NCRS Discussion Boards

Grounding Coil for Comp Check TI

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  • Gary S.
    Extremely Frequent Poster
    • July 31, 1992
    • 1628

    Grounding Coil for Comp Check TI

    Please save me the trouble of looking - how do I ground the dustibutor/coil during compression checking?

    Gary
  • Richard M.
    Super Moderator
    • August 31, 1988
    • 11302

    #2
    Re: Save ne@

    Gary just pull the coil high voltage wire off the coil center output going the the distributor cap. No need to ground anything.

    Rich

    Comment

    • Larry E.
      Extremely Frequent Poster
      • December 1, 1989
      • 1652

      #3
      Re: Save ne@

      [QUOTE=Richard Mozzetta (13499);880248]Gary just pull the coil high voltage wire off the coil center output going the the distributor cap. No need to ground anything.

      Rich[/QUO
      Would that be the same for K66>>Transistor Ignition??? Thanks>Larry
      Larry

      LT1 in a 1LE -- One of 134

      Comment

      • Richard M.
        Super Moderator
        • August 31, 1988
        • 11302

        #4
        Re: Save ne@

        Originally posted by Larry Evoskis (16324);880251 Would that be the same for K66>>[FONT=Arial
        Transistor Ignition??? Thanks>Larry[/FONT]
        Larry, No, what I describe is for conventional points ignition.

        K66 TI is very different and requires a different system, particularly if the TI Module is a original Delco unit. CSM states whenever you check for spark only pull one spark plug wire at a time to test. The Delco TI Module requires a consistent load at the coil output or the module final output transistor stage can be damaged. Pulling the "coil wire" off the coil to the distributor cap would result in NO load.

        The new upgraded TI Module circuit boards/modules use different technology so those should not have a problem, but I would not try it for fear of damage to those too. The only way to know what's inside the TI module case is to open it up and look. There are 3 versions.... Delco, K&B, and Lectric Limited.

        Delco
        DSCN4424.jpg

        K&B
        PC300002.jpg

        Lectric Limited
        MandH_TI_Amp_2.jpgMandH_TI_Amp_1.jpg

        Comment

        • Gary S.
          Extremely Frequent Poster
          • July 31, 1992
          • 1628

          #5
          Re: Save ne@

          I ask because after a search here I found one post that commented on of the potential failure of the coil without properly disabling it. I assumed, incorrectly, that this meant grounding it.

          Thank you Richard.

          Comment

          • Alan D.
            Extremely Frequent Poster
            • January 1, 2005
            • 2027

            #6
            Re: Save ne@

            Why not just disconnect the the three prong connector to the Amp?

            Comment

            • Richard M.
              Super Moderator
              • August 31, 1988
              • 11302

              #7
              Re: Grounding Coil for Comp Check TI

              Alan, Yes that way the Amp is totally disabled during crank.

              Comment

              • Tim S.
                Very Frequent User
                • May 31, 1990
                • 697

                #8
                Re: Grounding Coil for Comp Check TI

                This is a great item to have in your tool box.

                https://www.napaonline.com/en/p/BK_7...RoCjJwQAvD_BwE

                Comment

                • William F.
                  Extremely Frequent Poster
                  • June 9, 2009
                  • 1354

                  #9
                  Re: Grounding Coil for Comp Check TI

                  Still no answer on how to "ground the coil' on transitor ignition. On later GM vehicles with the HEI ignition, manual says coil must be grounded (not just pull coil wire out of coil) and think you have to do same on the older transistor ignition on C2's. . Do you use a jumper wire with clips to connect to end of coil wire and other end to a ground on block?

                  Comment

                  • James G.
                    Very Frequent User
                    • August 22, 2018
                    • 783

                    #10
                    Re: Grounding Coil for Comp Check TI

                    William,
                    You can use a Spark gap like Tim illustrated (the one I have is slightly different & made by WELLER) to check for spark OR if cranking over without trying to fire the engine (compression checks -run up oil pressure etc) then pulling the 3 wire connector to the TI box/harness is the safe way to proceed.
                    James A Groome
                    1971 LT1 11130 - https://photos.app.goo.gl/zSoFz24JMPXw5Ffi9 - the black LT1
                    1971 LT1 21783 - 3 STAR Preservation.- https://photos.app.goo.gl/wMRDJgmyDyAwc9Nh8 - Brandshatch Green LT1
                    My first gen Camaro research http://www.camaros.org/forum/index.p...owposts;u=4337
                    Posts on Yenko boards... https://www.yenko.net/forum/search.php?searchid=826453

                    Comment

                    • Patrick B.
                      Extremely Frequent Poster
                      • August 31, 1985
                      • 1986

                      #11
                      Re: Grounding Coil for Comp Check TI

                      I don't have my CSM with me, but I have always interpreted it to mean that the coil wire should be grounded to the engine or battery to protect the TI ignition when turning over the engine to build oil pressure, to do a compression check or to adjust the valves, without trying to start the engine. I have been doing that for almost 50 years on my 70 LT-1 and the original TI box still works, so it doesn't hurt anything.

                      Comment

                      • Richard M.
                        Super Moderator
                        • August 31, 1988
                        • 11302

                        #12
                        Re: Grounding Coil for Comp Check TI

                        For example, the Fuel Pump Pressure check in the CSM states....

                        "Disconnect distributor to coil primary wire so that engine can be cranked without firing."

                        This is the way I've always done it on a points distributor. Removing the coil wire and placing in ones pocket also makes for a good theft deterrent system.

                        I'm not familiar with HEI, but with TI it's safest to simply disconnect power to the amp module by pulling the TI harness plug from the module.

                        As an alternative you could unplug the #12 gauge Ignition Pink/Black-Pink(year dependent) connector to the TI harness connector (White resistor wire), along with the small gauge Pink/Yellow at the TI distributor plug as a method also. Don't forget the small Pink/Yellow wire as that's from the Solenoid R terminal so during Crank/START, the engine would run briefly but shutdown when keyed back to RUN.

                        Rich

                        Comment

                        • Richard M.
                          Super Moderator
                          • August 31, 1988
                          • 11302

                          #13
                          Re: Grounding Coil for Comp Check TI

                          Gary, et al,

                          I noticed this morning that the original Subject Title of this thread you started the other night changed from "save ne@" to .....Grounding Coil for Comp Check TI

                          So my initial response right after you posted applied to a points system as nothing was specifically said about TI. I guess after I replied that night, the next morning the Subject Title got changed by a Mod to what is is now, but I hadn't noticed it. Then I thought people were confusing the thread talking about TI. Sorry if I confused others by not replying specifically about TI.

                          It all makes sense now..... I think!

                          So......Since we all know now it's TI we're talking about, I have to reiterate that I would just take power away from the AMP to do any kind of non-start required cranking. But......

                          Patrick, I had never heard of grounding the TI coil secondary output before. It's probably in a section regarding non-start crank for procedures you mention and not in any TI Section. Now that I think more about it, it makes electrical sense as the Delco(or any) module would maintain a constant load that way, as opposed to alternating load when pulsing via the amp output transistor and collapse the magnetic field of the coil. Also, I suppose since the field never collapses there will never be any back emf to the amp either to hurt it.
                          So I learned something new about TI in this thread and I thank you for that.

                          Rich

                          Comment

                          • William F.
                            Extremely Frequent Poster
                            • June 9, 2009
                            • 1354

                            #14
                            Re: Grounding Coil for Comp Check TI

                            What part of engine can you ground the coil to-distributor hold down bolt/ other?

                            Comment

                            • Patrick B.
                              Extremely Frequent Poster
                              • August 31, 1985
                              • 1986

                              #15
                              Re: Grounding Coil for Comp Check TI

                              Originally posted by William Ford (50517)
                              What part of engine can you ground the coil to-distributor hold down bolt/ other?
                              Most places on the engine are grounded. The hold down bolt should be a good ground. Check with an Ohm Meter to the battery ground. Any place you ground your timing light to would be fine.

                              Comment

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