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Tach Fix
Retro Rockets is an authorized PerTronix dealer.

Fixes for 12V Signal Style Tachometers

     If the car’s tachometer is reading to a higher RPM when the engine is running, or the tachometer works okay to a certain RPM then stops or starts reading incorrectly, we recommend installing a resistor in line with the tachometer wire and coil negative.  This helps knock down the voltage spike on coil negative to look more like a set of points allowing the tachometer to read the Ignitor’s signal correctly. 

     The type of tachometer will determine which resistor is needed.  We have found that a 10K ohm ˝ Watt resistor fixes most problems and suggest starting with one of these.  If you find it doesn’t fix your problem you might need to use one with higher resistance like a 15K ohm ˝ watt or 20K ohm ˝ watt.


A resistor will work in the vast majority of applications, but there are a small number of tachometer designs that will require a capacitor.  We recommend using a .01 Microfarad 500VDC or 1000VDC capacitor.



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Postal address:
Retro Rockets, P.O. Box 200, Norfolk, CT 06058
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