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Tach has quit working after an HEI install

Discussion in 'Early CJ5 and CJ6 Tech' started by spaceangus, Jun 4, 2012.

  1. Jun 4, 2012
    spaceangus

    spaceangus New Member

    Albuquerque NM
    Joined:
    Jan 24, 2012
    Messages:
    12
    I just installed a CRT HEI distributor, and now the tach is not working. I believe that I have this wired correctly, but if not, what should I be looking for? This is in a 1970 CJ5 V6 oddfire, and the tach is marked with an SW.
    I have searched the forum for this and am now confused about whether the tach will even work with the HEI. Any advice will be helpful.
    Thankyou
     
  2. Jun 4, 2012
    pblalock

    pblalock New Member

    Joined:
    May 9, 2012
    Messages:
    31
    I just install an hei and a tach (3 weeks ago) in my 71 odd fire. My tch had 4 wires... one for the the light in the tach, one goes to ground, one goes to positive(hot) source (only when ign. is on) and the other goes to the "tach" terminal on the distributor..oppo. side of "bat"
     
  3. Jun 4, 2012
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
    Joined:
    Mar 4, 2003
    Messages:
    5,466
    Tach signal should work - I am using it to drive the EFI on mine. You may want to look at the top and make sure it all looks good. CRT should be able to help with that as well as the tach company.
     
  4. Jun 4, 2012
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
    Joined:
    Nov 27, 2006
    Messages:
    2,793
    I've heard that some tachs won't work with HEI.
     
  5. Jun 5, 2012
    Posimoto

    Posimoto Hopeless JEEP Addict

    Minden, Nevada
    Joined:
    Aug 7, 2003
    Messages:
    4,538
    I have a SunPro tach hooked up to my HEI and it works fine. It's hardly an expensive tach. Used it before i switched to HEI on my stock coil/dist.
     
  6. Jun 5, 2012
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
    Sep 22, 2002
    Messages:
    8,360
    I've never seen a tach that wouldn't work with HEI.
     
  7. Jun 5, 2012
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
    Messages:
    12,529
    Don't think I have either. Hook up to tach terminal, power, ground, lights, go.
     
  8. Jun 5, 2012
    rusty

    rusty Well-Known Member

    norfolk,va
    Joined:
    Dec 16, 2006
    Messages:
    1,652
    I have heard that older tacs need some sort of a box that can change the signal from the h.e.i. so the tac can read it. Don't know , never have seen one. Might be worth looking into.
     
  9. Jun 5, 2012
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
    Joined:
    Mar 4, 2003
    Messages:
    5,466
    I had one that didn't work with HEI as a kid. I remember it said 'NOT FOR HEI' on the side of the box. Worked real well till it died of 'blunt force tramma' due to a 'roll over issue' I had (as a kid ;) ).

    PS - I remember it so well as it was on sale and I could afford it... funny which brain cells stay alive after all this time.
     
  10. Jun 5, 2012
    spaceangus

    spaceangus New Member

    Albuquerque NM
    Joined:
    Jan 24, 2012
    Messages:
    12
    Thank you for all of the quick replies, I'll rip back into it and retrace the wiring. I must have just gotten a wire mixed up. Are the SW marked gauges aftermarket or stock?
     
  11. Jun 6, 2012
    jc588

    jc588 Member

    Ruston, La
    Joined:
    Jun 24, 2009
    Messages:
    159
    When I swapped to HEI, mine quit working. I don't know if shorted something or what. Bought a new one and it worked fine. It's a sunpro also.
     
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