Yesterday i managed to build a jumper i wire with terminals and connect it through the Ballast Resistor in order to remove it from the circuit as advised. However, before doing this modification, i measured the voltage accross the Petronix 3 ohm on my 240z and it measured between 3.8 to 4 volts DC with the engine on. Is this normal?? Could the Coil be damaged or weak and needs replacement? I measured the Battery Voltage  with the car at idle and its 14 Volts DC

 

If the voltage is weak which model is recomendable?

Hmm. I just purchased generic coil and it also has 3 ohm resistance and spark is weak. Did also bypass the ballast, did you manage to get your tachometer working somehow?

Yes! i reverted it! Replace the original ignitor and former coil and the tach is working perfectly and not jumping! Really weird! The Pertronix coil is model 40511, 3.0 ohms.