oh yeah, Stu - the points get full COIL output voltage [10,000V?], it's the coil input that gets the 12V
That's not correct, the points ground out the 12 volt Primary Winging of the coil, which is more like 9 volts when it's running through the ballast resistor. The HIGH voltage Secondary Winding is grounded at the sparkplug when it jumps the gap. The High Voltage spark happens every time the points OPEN. This is due to the collaps of the magnetic field inside the coil, which in turn makes a low amp-hi voltage spike that is allowed to jump the gap at the spark plug at just the right time.
If you install an Internal Resistor type coil you will not get the full 12 volts when you try to start the truck. There is no way to by-pass this resistor. I believe most of the Internal Resistor type coils were used on small engines (farm and gargen tractors etc.).
Your Tach should be connected to the distributor side of the coil, not the battery side.
Hope this helps...
Happy Holidays!
Mike B
