Dual points? Or single points? Generally dual point distributors were high performance units.
Really, it all comes down to being a better switch.
The Dwell Angle of a single set of points can only be so large, since they need to open far enough to do the job.
Dual point units use two sets of points with an overlap. That way the time the circuit is closed is longer, allowing the coil to charge for a longer time between firing cycles. This is important at higher RPM's, since it can reach a switching speed of 400 times per second.
Chrysler OEM electronic ignitions are simply a faster switch. They use an electric signal from the distributor to fire the coil with a transistor. Because the transistor can turn on & off faster than the moving point set, the coil charges for a longer time between firing cycles.
So called HEI systems are basically the transistor switch, with a better coil. HEI or E-core type coils can draw more current, and the control circuit is designed to handle that extra current. Instead of turning that electricity in to heat in a ballast resistor, the energy goes in to the coil. Dwell angle or coil charging time is improved, and the higher current in the coil primary translates to more current to the spark plug.
To move beyond a switch & a magnetic coil, you need a power supply. Units like MSD use a power supply to build 300+ volts in a capacitor. They use the coil as a transformer by dumping that capacitor in to the coil very quickly. This is a CD or Capacitor Discharge ignition.
The big question is - How much spark do you need?
That 318 ran ok with a set of points. The OEM electronic unit required less work during a tune-up (no points) but was still limited by the same ballast resistor & used the same coil.
There are many people here reporting improved performance from adding the GM ignition module & coil. Not a surprise, the coil is much better and not wasting power with a ballast resistor.
It is possible to trigger most CD ignitions with a set of points, if you wat to leave the stock distributor in place.
In my experience, it is hard to have "too much" spark. High spark current ignitions seem to provide better starts and better mileage on any car.
Modern systems all went to multiple coils more than a decade ago. On a V8, that means 8 coils, which obviously get to charge 8 times longer. Detroit & Tokyo both keep putting more powerful ignitions on cars, even thought it costs them more money. Must be a reason.
B.
