Tach and Speedometer

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  • October 23, 2011 at 10:40 am #233774
    Jim Dudley
    Participant

    @jddwew

    I have been working on my TD and finally got the suspension and most of the electrical working and ready to drive.  I question the accuracy of the Tach and Speedometer.  I can check the speedometer with my GPS, but how can I check the accuracy of the Tach?

    Thanks, Jim

    October 23, 2011 at 1:01 pm #247297
    newkitman
    Participant

    @newkitman

    My best guess (and its just a guess): attach a tach dwell meter to the engine and run the engine slowly through the full range (working up then dow) and compare the tach in the instrument panel with the tach dwell meter.

    Allen Caron
    VW based 53MGTD - "MoneyPenny"
    "If one thing matters, everything matters" - from the book The Shack

    October 23, 2011 at 1:07 pm #247298
    Paul Mossberg
    Keymaster

    @pmossberg

    Good idea Allen!

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    October 23, 2011 at 2:43 pm #247299
    Royal
    Participant

    @royal

    Or, if everything is stock, on a VW based TD, after you check the speedo against the GPS, you can check the tach against the speedo (or against the GPS).  With my gearbox (standard for many of the 68-early 70’s) and 165×80 tires gives me 60mph@3050RPM in 4th or 60@4040RPM in 3rd. 

    October 23, 2011 at 4:32 pm #247300
    Jim Dudley
    Participant

    @jddwew

    I guess I forgot to mention that it is a Ford 2.3 engine in a Fiberfab kit.  If they are off, is there a solution?

    Jim

    October 23, 2011 at 6:34 pm #247301
    Royal
    Participant

    @royal

    Oops! …. Then Allen’s way with a dwell tach is the best. Roy

    October 23, 2011 at 7:46 pm #247302
    newkitman
    Participant

    @newkitman

    Ah…if therre off, what to do? I would suspect the tach dwell meter would be the accurate one. I have a sheet that comes with my instruments that I can send to you. PM me. Other than that, this is what I have told to do if mine is off where I feel I need to adjust/calibrate it.

    The tachometers have an adjustment screw on the back side. You’ll need to hook up an accurate shop tach (inductive pick up will work) to the engine. Compare readings at the middle of your rpm range and adjust as required.

    Allen Caron
    VW based 53MGTD - "MoneyPenny"
    "If one thing matters, everything matters" - from the book The Shack

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