Ford Duraspark 2 Ignition System question

Why is there a 1.3 ohm resistor in the B+ wire from the ignition switch to the coil when the ignition switch is in the run position???

 

to protect the coil. the relay sends full volts to the coil while cranking the engine usually. the volts are dropped down while running to extend coil life.

 

thanks! I want to make my own harness and not use junkyard harness and connectors... and thats all I needed to know!..

 

That 1.3 Ohms is usually a long pink wire off the ignition switch on most older Fords if you want to save yourself the hassle and cut it from a parts car to add to your loom.