RUN- - - - -do not walk, away from a Pertronix system! If you want an electronic ignition system, use the original equipment GM distributor used on the 230/250/292 engines.
You need a Delco coil marked "12V" on the housing. It operates at approximately 9.5 volts, which is why you need a ballast resistor to drop the current carried by the points during normal running. When a very cold (or hot) engine is being cranked, the load on the starter drops battery voltage to the mid-9V range, which is why the resistor is bypassed during cranking. That's the purpose of the small stud on the side of the stomp start switch. A wire from that terminal to the coil (+) supplies full battery voltage to the coil when the engine is being cranked, then the circuit goes back through the resistor to supply the coil with 9.5 volts or so while the charging system is producing 14+ volts during normal running. Without the resistor, the points will pit and burn very quickly.
The "12 volt coil is actually a 6 volt" myth has been repeated so often that some people believe it. The Delco coil with "12 V" embossed on the can is a 9.5 volt unit which is correct for ALL GM vehicles with a 12 volt point type ignition system. There are two types of coils for GM vehicles- - - - -"Delco" and "Wrong"- - - - -ditto for voltage regulators!
Jerry
