Take this to the Bank: any time an engine quits suddenly, its likely an electrical problem -unless parts of the crank or rods are showing outside the block! So circumstances point to either a bad distributor or something in that area & requires distributor removal from the engine for final diagnosis.
#1 likely distributor problem- the infamous roll pin that attaches the drive gear to the distributor. Once the distributor is out, hold the gear up and attempt to look through the hole in the gear and roll pin. If there’s no visible path through, either the roll pin is sheared, partially sheared (which drastically retards the timing) or you have a weaker spring-pin in there. Either result requires replacing the pin with a real roll pin. This is a generic 25¢ part at any auto parts store or repair shop. As an upgrade, add a second smaller roll pin inside the first, to further strengthen the assembly. Otherwise, you will be going through this exercise again down the road, guaranteed. This included all distributors incidently, aftermarket or stock, for racing or street.
#2- assuming the pin is OK & you did the upgrade but still get no fire.
Inside the distributor is a capacitor. The wire going to it sometimes cracks at the point of juncture to the capacitor body. Cap's do not show up on VOM checks since they are open circuits but are an integral part of spark-generating.
Replace it and all the short wires inside the distributor. Sometimes after 35 years, the insulation and/or grommet that allows electricity to pass from coil to distributor will harden & crack, allowing an intermittent short that also will not show up on your VOM, so look closely at this, too.
It bothers me to hear you only have 9 volts with no ballast; you should have a full 12 or 13 volts with no resistor, so the power wiring feeding the coil is also suspect. Many electronic ignitions are inoperative without at least
10-1/2 volts. I once worked on a Pantera with no fire, that after a long search turned out to have a 3” section of wire from the voltage regulator to the coil corroded internally- the wire insulation looked OK but inside, the wire had turned to green dust from corrosion. For the purposes of a VOM it was still a ‘conductor’, but would not conduct enough volts to operate an ignition.
Further inside the electrical system, the ignition switch is certainly a possible trouble spot although I can’t think of a reasonable failure mode involving the switch that would only hold up a few volts going to the coil, and still operate the starter. And since new ignition switches are almost unavailable from any vendor in the world, I sincerely hope its not that. The column need not be dropped; once the plastic covers are removed, the ignition switch is held into the column with theft-proof shear-screws that must be drilled out for switch removal.
Hope this is of value.
