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Tachometer Calibration

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    Tachometer Calibration

    None of the tachs read the same on my boat. The Port pair was worst with over 200 RPM difference at 2300 RPM. I was going to purchase digital tachs, but I found a local business which, for a very reasonable price, recalibrated them for me. What impressed me was that he asked what RPM I nomally run at so that he could be sure they are all 100% exact at that rpm.
    Shepard Instruments Langley BC
    T 604 364 5845
    Claudio Ugo
    2001 Bayliner 4788
    Bow & Stern Thrusters
    330 Cummins
    Langley British Columbia

    Yes - there are two small holes in the back of the tach with 'plugs' that can be 'tweaked' with a small non metallic screwdriver to make the adjustments.
    I have found that the connection blocks for the wiring often are a culprit in getting good tach readings.
    Northport NY


      I tried adjusting my 1989 Faria analog tachs against my hand held laser tach many times without much success. 100rpm off wasn’t my idea of good so I bought two digital tachs for the upper helm and now I truly know the rpm in ALL rpm ranges.
      Jim Gandee
      1989 3888
      Hino 175's
      Fire Escape


        one of the things I have learned about tachometer circuits is that they take a very small amount of power thru the wires, and even the slightest bit of corrosion can cause a resistance which will adversely affect the readings.... a circuit that keeps "making and breaking" due to bad wires or connections can cause the tach calibration to be thrown off, or ruin it if it cannot be recalibrated...

        I have found that taking the ends of the wires loose in the circuit so they are not attached, and then load testing the individual wires with 5-8 amps, and afterwards doing a resistance test... this will show the integrity of the wires and the connections of the wire end terminals...

        the terminal connections to the system components can easily be made better by insuring they are snugly connected and using a slight coating of silicone grease on them before making the final connection....

        if the wires are good and the connections are without corrosion and tight, the tach will work dependably for a long time.

        NU LIBERTE'
        Salem, OR

        1989 Bayliner 2556 Convertible
        5.7 OMC Cobra - 15.5x11 prop
        N2K equipped throughout..
        2014 Ram 3500 crew cab, 6.7 Cummins
        2007 M-3705 SLC weekend warrior, 5th wheel
        '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
        Heavy Equipment Repair and Specialty Welding