67 factory cuda tach

Electrical and Ignition

  1. rt440mag

    rt440mag Member

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    Want to test this 67 factory tach and spec sheet says case in ground, Dark blue is 12V, Gray with trace is to coil - neg terminal. Pictures are front and back same orientation Which terminal is 12v, top stud or side tab.

    67 Tach.jpg

    Tach Face.jpg
     
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    • mopardude62

      mopardude62 FABO Gold Member FABO Gold Member

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      The dark blue wire (12V) attaches to the long stud at the top, the spade is for the gray ignition wire coming from the coil negative.
       
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      • rt440mag

        rt440mag Member

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        What I suspected, but wanted to be sure. Thanks for the feedback.
         
      • RedFish

        RedFish Well-Known Member

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        So if you take that gauge apart for any reason, you'll find those two contact studs are mounted in a small piece of phenolic board. Its simply attached by wire leads allowing it to drop through the case in either position. We'll assume that why the case wasn't marked.
        'S' = Signal and for these tachs = Shorter stud whether you mark it before disassembly or not. The mo you know :)
         
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        • RAT ROD AL

          RAT ROD AL I know just enough to be dangerous FABO Gold Member

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          I'm in the same boat ! do these look like the correct wires for the tach ?rt440mag
          20191107_180441.jpg 20191107_180555.jpg
           
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          • rt440mag

            rt440mag Member

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            yes, grey wire to the spade connector on tach and other end through the firewall connects to negative terminal of coil. The blue wire goes to accessory side of the fuse box or ignition and provides +12 to long stud on tach.
             
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            • RAT ROD AL

              RAT ROD AL I know just enough to be dangerous FABO Gold Member

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              Now on my fuse block , There is another blue wire coming out that has the same type push on stud connector . When does the blue wire need to power up ? RUN poss ?
               
            • rt440mag

              rt440mag Member

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              When the key turns on it should energize the wire and you should see +12 volts at the wire terminal.

              But If you're just testing the tach, as your original post said, just go under the hood and attach the grey wire to negative terminal of coil and spade terminal on the tach, a ground wire to the tach's case and car. attach the cap''d (blue wire) terminal to the positive terminal on the tach. Start the engine, touch the wire to positive terminal of the battery and observe the dial. But remember if you're using a car with electronic ignition, the tach may not show accurate readings. It was designed for breaker point ignition.
               
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