It is important that this system be properly maintained by means of a regular tune-up, which consists of replacing the spark plugs, distributor cap, rotor, points and condensor, along with inspecting the wiring periodically to make sure that nothing is damaged or worn out, or has a bunch crud or corrosion building up on a connection. These cars will keep on chugging down the road in an astonishingly poor condition, but it is costing you in a lot of ways to do that, namely, poor fuel economy and poor performance. Since all of the parts involved in this tune-up are really, really cheap, and readily available from any auto parts store, and the level of expertise needed to perform this tune-up is amazingly low, it makes no sense not to.
There is a problem that people encounter, which seems to be quite baffling to them, but results in 'car won't start'. If, when you turn the key to the start position, the car cranks fine, sounds like it started, but dies instantly when the key returns to the On position, that is almost always one of two things. Either the resistor wire is dead, and needs to be replaced, or, the car has a factory tach, and the tach has died. You could get a factory tach on these cars if A) you had a 65 or 66 Shelby GT-350, you purchased one of the over-the-counter Cobra or Rotunda tachs from your local Ford dealer, or your car had an original rally pac. How the factory tachs were wired was, two of the wires that came out of the back of the tach were connected in-line with the resistor wire at the ignition switch. You unplugged the resistor wire from the red wire with the green stripe near the ignition switch and plugged the two tach wires into the two ends of the ignition wiring. When the tach dies, it takes the car's ignition system with it. The fix is to unplug the tach wires and plug the resistor wire back into the red wire with the green stripe that comes from the ignition switch.