No improvement. I can't see any arcing, but considering the strength of the shock I got, I'd bet arcing somewhere is the cause of the pinging. The pings only come out of the B bank exhaust.

 

Sounds like its time for a new distributor and plug leads?

 

If you got WHACKED, there be the issue.

As said:

New cap
New rotor, and do teh Mod.
New leads, all 14 of them, and good quality only.
New Spark Plugs, and gapped to 0.025".
Clean the throttle discs and throttle bodies, BOTH side.
Ensure the Disc to Bore is set at 0.002".
Reset the throttle rods.. BOTH side so they are balanced 100%, remembering that this is NOT a V12, it is a Double Six, so balance is critical.

That's the basics for this engine since 1976, when it went from Carby to Infected.
The Marelli, I know NOTHING, and love it. All I know is what I read in here, as can you.

 

Back after many months of putting this car on hold. Good news! The source of the pinging has been found. After thinking about the situation, I thought of a way to test for the location of the arcing. I took a screwdriver with an all plastic handle, clipped a jumper cable to it, with the other end of the cable clipped to a good ground, and wrapped my hand in a towel. Then, I probed around the engine bay for sparks, and, sure enough, the wire from one of the coils going into the top of the distributor would up like the 4th of July when I brought the screwdriver near and the car wanted to die. A new set of wires is on the way, and I'll report on the results.