So. Correct me if I'm wrong.
12 volts for the coil comes from the starter. The starter has 12 volts at run. Turn the key to start, starter moves the flex plate which in turn moves the cam and the rotor to the tabs under the cap. Coil discharges itself when it moves in line with the cap tabs.
What would prevent this coil from discharging?
These two are entirely wrong:
12 volts for the coil comes from the starter.
The power supply for the B+ terminal at the ignition coil comes directly from the IGN1 terminal in the ignition switch via the PNK 3 lead. The IGN1 terminal also supplies the IGN bank within the fuse block - using the same PNK 3 circuit. IGN1 is hot whenever the ignition switch is in either the RUN or START positions.
The starter has 12 volts at run.
The starter (the solenoid actually) always has full battery power available on the line (inlet) side of the it's main contacts (it comes in on the big black cable that runs up to the battery positive terminal). The other side of the contact set is connected to the main starter motor windings. When the contacts are closed - by the solenoid - the battery is then directly connected to the starter windings.
There is a small lead (PPL 6) that is connected to the "S" terminal on the solenoid. The other end of the PPL 6 lead passes through the firewall and connects to the NSS (neutral safety switch) at the base of the steering column. It exits the NSS as the YEL 5 lead. That YEL 5 is connected to the SOL terminal in the ignition switch.
When the key/switch is moved to START, the SOL terminal is energized. Power then flows from the SOL thru the YEL 5 lead, across the NSS contacts (if the gear shift is in either P/N) and into the PPL 6 lead. The PPL 6 lead supplies the solenoid with power on the "S" terminal.
When the solenoid coil is energized, it pulls a plunger in. When that plunger pulls in, two things happen:
1. Indirectly, through linkage, the starter pinion is moved outward where it engages the ring gear on the flexplate/flywheel.
2. A copper bar - attached to the other end of the solenoid plunger - bridges the contacts and begins to supply the starter motor windings with battery power.
So, at that point, the drive pinion is engaged with the flex plate and power is available to the starter windings. With power applied, the motor spins and drives the pinion shaft & gear. The pinion gear drives the ring gear/flexplate assembly. And, because the rotating flexplate is bolted to the end of the crankshaft...the engine turns as well.
When the operator senses that the engine has fired - and is running on it's own - the ignition switch is released and allowed to snap back to the RUN position. The PPL 6 wire goes dead and stays that way until the next starting event.
Meanwhile, up at the distributor, the ignition coil - which has been receiving power from the IGN 1 terminal (on the PNK 3) ever since the key was moved from the OFF position, is providing the spark plugs with 40,000 volts for combustion.
This one is essentially correct - only the crankshaft is missing:
Turn the key to start, starter moves the flex plate which in turn moves the cam and the rotor to the tabs under the cap.
This one is kind of true.
Coil discharges itself when it moves in line with the cap tabs.
Actually the coil (and the rest of the distributor's electrical components) have no idea where the rotor tip is - in relation to the cap's terminal posts - when it discharges a spark. That's why we time the ignition ourselves.
The secondary ignition circuit (in the distributor) generates- and makes available to the plug wire posts - 8 sparks per revolution of the distributor shaft. All of these sparks are evenly spaced and one will fire every 45 degrees of the rotor's 360 degree full rotation. No matter where the tip of the rotor is - in relation to the terminal posts (which are of course also evenly spaced and 45 degrees apart), the coil will attempt to discharge the generated voltage. The 45 degree spacing is a function of the pickup coil and the spikes in the reluctor ring.
The object of timing an engine's ignition system is to get 3 things synchronized:
1. The spikes on the reluctor ring (and by extension, the tip of the rotor), with the
2. Plug wire terminal posts in the distributor cap, so that when those two are in line the
3. Associated piston is at TDC (actually a bit before)
What would prevent this coil from discharging?
Actually almost nothing would prevent the arcing of 40,000 volts - nothing that would be found in a distributor cap anyway. If no spark is evident at all, it would be safe to assume that no voltage is being developed by the ignition coil's windings. The problem is not with power transmission, rather it is most likely with power generation. You yourself have remarked several times about the lack of even a backfire.
Bottom line: if an HEI distributor is supplied with 12 VDC at the B+ terminal, that is basically all that you can do - externally. Any other condition - that would prevent the generation of proper voltage to create a spark - would almost surely be internal to the distributor.
