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Wiring up Tachometer

Discussion in '40- & 55-Series Tech' started by RyRy, Aug 18, 2003.

  1. RyRy

    RyRy

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    Does anyone know how to wire up a tachometer in my Bj40 ?
    My tacho has 5 wires. 12V + and - , +58 , -31 , and +30

    any ideas?

    Cheers

    Ryan
     
  2. cruiser_guy

    cruiser_guy

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    Is this an aftermarket tachometer? If so, is it suitable for diesel? Most tachometers use a coil signal for RPM's (something not available on diesels!). The BJ60's use a sender on the bellhousing to give a signal to the tachometer.
     
  3. RyRy

    RyRy

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    its an aftermarket one my friend had laying around. I thought i might be able to use it. Does anyone know where the wires would go?
     
  4. s79bj40

    s79bj40

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    do you have a sender of some kind for your diesel? tachos use the pulses from the coil usually and divide by the number of cylinders to give the rpms. Sounds like kindof a lot of work to get one going. Tachos for petrols wont work.

    aftermarket tachos for diesels are $1000+ with special fitment, if the engine didn't come with one from the factory.

    Sam
     
  5. RyRy

    RyRy

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    I dont know. Its a stock 78 Bj40. Did they come with a sender unit? *shrugs*
     
  6. sixpack

    sixpack

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    my b engine had some sender behind the injection pump, but i never found a way how to work it. When measured with a volt meter, it seems to rise parallel to the rpm.
     
  7. arutgers

    arutgers

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    Hi Ry,
    Best way is to attach the tach to the alternator. Some alternators have a connector at the outside where A/C voltage is supplied. The frequency is relative to the enigine rpm's, though it is NOT equal because pully sizes are different. So you have to calibrate the tach, and for that you need an adjustable tach like http://www2.vdo.de/vdo/end_consumer/ec_product&fza=&ID=725.aspx (sorry, it's in german ???).
    Most garages have the equipment for calibration.
    If your alternator does not have the connector at the outside, you must disassemble the alternator to bring out a wire. More difficult though. :D
    Ton
     
  8. cruiser_guy

    cruiser_guy

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    RyRy,
    Where are you? I'm in Vancouver, B.C. and I have a spare bell housing from my BJ60 which has a space for the sensor to mount. You may need a different flywheel as well as I think is receives a signal from a magnet or something imbedded in the flywheel. If you're interested let me know.
     
  9. RyRy

    RyRy

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    Im in perth, australia,
    but i appreciate the offer cruiser_guy!