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need help hooking up tach

Discussion in 'Intermediate CJ-5/6/7/8' started by springerfever, Nov 19, 2005.

  1. Nov 19, 2005
    springerfever

    springerfever Member

    suwanee, ga
    Joined:
    Aug 1, 2005
    Messages:
    273
    Guys and gals......trying to get a Faria tach hooked up on my 75 CJ5 and so far no luck. Alan (Hippo393) was nice enough to send me a tach from a 76 dash that he had. I'm hoping to get it working and install it in a cup on the steering column.

    As you can see from the pictures, its in great shape and is just what I was looking for (short of the factory cup tach for that year... and I'm beginning to think those don't exist!)

    My problem is I can't get it to work. The needle bounces freely, but when I hook up the two terminals, the engine suddenly dies. As you can see the sticker shows one lead going to the battery via the ignition switch and the other is off the coil. Only problem is, I don't have a coil!
    I installed a HEI distributor a while back and did away with the coil and the juice box. There are two terminals out of the distributor...one to battery and the other to tach. That is the one I used going to the tachometer.

    Also the two terminals on the back of the tach are not marked. One has a black gasket under it the other one, a tan gasket. The hole at 12 o'clock is for the light socket.

    Anybody got any suggestions, sure would like to get it working!!
     
    springerfever, Nov 19, 2005
    #1
  2. Nov 19, 2005
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
    Messages:
    4,275
    Try switching the terminals on the tach, it sounds like you are grounding out the HEI through the tach. The HEI terminal substitutes for the (-) terminal of the coil in a conventional tach hookup.

    Just one caution though, an electric tach is designed to work with a certain number of cylinders. Once you get it running, I'd double-check it against a dwell-tach to be sure it reads what it should. Aftermarket tachs have a switch to select 4-6-8 cylinders, btu a factory unit might not. Also, in '76 I think the tach was dash-mounted, on one side of the column, and a clock was on the opposite side. Can't remember which side was which.
     
    w3srl, Nov 19, 2005
    #2
  3. Nov 20, 2005
    gte636p

    gte636p Member

    smyrna, Ga
    Joined:
    Sep 23, 2002
    Messages:
    492
    coming over from my other thread... i got mine working today!! but it's off by a couple hundred rpm (registers 2000 when second tach registers 2500, oh well). anyway, to answer your question, i did the same thign today... the second you let the tach lead from the coil ytouch ground the engine will die. if it hits ground anywhere there isn't a potential drop when the magneto gets the signal, it's already going to ground. or at least that's how i explained it to myself once i saw it happen.

    just use one terminal from the battery the other from the second spade on the hei and you should be set to go. hope yours is more accurate than mine turned out to be.
     
    gte636p, Nov 20, 2005
    #3
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