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Tachometer questions.

Electrical and Ignition

  1. bullet18

    bullet18 Well-Known Member

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    I can't seem to find much info on how to install a tach on my motor. Ive got a 78 motorhome 440 in my 70 challenger with a chinese hei knock off distributor. My dash doesnt have a tach but i would like one so i can set total timing and not accidentally float the valves. Where do most aftermarket tachs get wired to? The coil?
     
  2. Rich G.

    Rich G. Active Member

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  3. Adam

    Adam Well-Known Member

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    Last edited: Mar 16, 2019 at 9:15 PM
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  4. aussiemark

    aussiemark Well-Known Member

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    The after market tacho will or should come with some instructions (if new) there will be wiring for illumination you will have to wire this into your light bar so it comes on when you switch the lights on. there will be negative to ground, positive to switched power and negative trigger to the negative on your coil.
     
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  5. moparleo

    moparleo Well-Known Member

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    I don't believe that the 70-71 Rallye tach's will work with electronic ignitions as Chrysler was still running point ignitions until 1972. An adapter is required. Need more research.
     
  6. Adam

    Adam Well-Known Member

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    The Mopar electronic ignition & distributor do work on a 70 & 71 cars with a Rallye tach. 100%, I have personally done this on both my cars, with no adapters. The coil does not know what type of dist is triggering it, and the tach gets it’s signal from the coil.
    I do not know if the MSD or other aftermarket spark systems work with the factory tach, I suspect they do, but I have never used them.
     
    Last edited: Mar 17, 2019 at 4:53 AM
  7. bullet18

    bullet18 Well-Known Member

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    Thanks for all the info! I guess i can just use an aftermarket tach.
     
  8. AUSTA

    AUSTA Well-Known Member

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    If using aftermarket source 1 with settable high rpm trip point so that you can connect a light or if you fit an MSD at later stage you can set RPM limit
     
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  9. bullet18

    bullet18 Well-Known Member

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    Will do. Thanks!