Tachometer (aftermarket orginal look) Whats needed to install?

Discussion in 'The Bench' started by J Rider, Apr 10, 2015.

  1. J Rider

    J Rider New Member

    Hello everyone and anyone that can help me.

    I have a 1972 Buick Skylark, it has the original dash components. gauges.
    I bought this after market original tachometer as I wish for the original look for this car. Its going to replace the clock,
    which in my opinion is next to worthless (even if it worked all the time).

    This is the one I bought https://www.opgi.com/skylark/S220052/

    I can't seem to find any info on how to install, theres been a few pages here that were helpful but I'd like a more clean cut,
    potentially step by step/ grocery list on supplies and hook ups as well as best way, if needed to run through the firewall.


    The back of the tach has this, look at the picture posted above, however it has both L spade males as opposed to this picture.

    I know that 1 is supposed to go to the distributor and is supposed to go to the one labeled 'tach'
    Theres 2 stickers by each of the L spades, one is labeled 'S' the other is '+'
    The tach itself is supposed to mount along with the speedo's ground and can be connected with a wire as I had previously read.

    My questions are:
    is it the 'S' L spade that connects to the distributor?
    What does the '+' L spade connect to?
    What wiring gauge is best to use and whats the best path to take when wiring?

  2. 72newbiebuick

    72newbiebuick Gold Level Contributor

    I just did this install and it was a cinch. "S" is the signal wire and it goes to the negative side of the coil. The "+" spade is a keyed power source - either run a wire to the "IGN" spade on the fuse block or find a wire that is run off the ignition and splice into it. I have a TH350 72 Skylark and found a yellow and black / white wire taped up in the harness near the gas pedal. This was for the TH400 kickdown switch, and the yellow is the wire for the radio power. I used that since it's keyed and I didn't have a need otherwise.

    There should be two bulb sockets in your harness (probably in use now for the clock) that snap right in.

    So, + goes to keyed power
    "S" goes to neg of coil

    I used 14 ga wire but realistically you could probably use 16 also.

  3. J Rider

    J Rider New Member

    Thanks a whole lot Mark for the quick reply and clean cut answer! I'm trying to get to it this weekend and will let you know how it goes.

  4. rkammer

    rkammer Gold Level Contributor

    No hijack intended but, I have an original, working tach that only has one spade lug. I'm sure that lug goes to the distributor negative terminal but, does that mean that the factory tach doesn't get a 12 volt connection? I believe the ground is gotten from the case to a ground connection at the back of the cluster.
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    That's correct.
  6. 72newbiebuick

    72newbiebuick Gold Level Contributor

    No sweat, Jon. I was anal and used corresponding color wire, bought the molded male / female plug kit with the terminals to boot. This is the LAST time the dash comes apart for me!

  7. jcdac

    jcdac John DaCosta

    I am planning for this project right now. Is the wire to the coil already in the harness? I don't see any other wire connected to the coil. There is a loose brown wire by the fuse box, not quite sure why, but could this be the wire to use. If I have to run a new wire to the coil, it is just a 12v wire and brown is the right color? thanks
  8. GStage1

    GStage1 Always looking for parts!

    I know on the early production units, the light socket holes were not the same as the stock sockets so you had to splice the new bulb sockets into the original light harness.
  9. 72newbiebuick

    72newbiebuick Gold Level Contributor

    I cannot say that brown wire would be what you want, as I am unsure if harnesses would ever have the tach wire included (depending on the car setup from factory). If that was the wire you would have to make sure you had the "other side" out in the engine bay. Might be easier to just run a brown wire from the tach to the negative side of the coil directly.

  10. cpk 71

    cpk 71 im just a number

    The ground is a metal strip that jumps from the tach to the speedo case,but you can ground it to anything metal back there!
  11. yachtsmanbill

    yachtsmanbill Well-Known Member

    Perhaps here?? Bill in TR




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