Bring on that sweet music

 Words not needed here. I'll let the exhaust note speak for itself.

Finally back on track

In addition to the carb issues, David also suspected there was an ignition issue caused by poor EM shielding. He suspected this because of these clues:

-Erratic tach
-Erratic timing light behavior
-Odd markings in the 1-4 distributor cap
-1-4 bank plugs simply don’t look as nice as 5-8 bank

With the newly repaired carbs installed (again), new 1-4 bank distributor cap, and higher quality ignition wires, the problems seem to have gone away. The tach is glass smooth, plug cuts look a lot better and now on to final tuning (again).

As David says, “90% of carburetor issues is ignition." In this case, sounds like it was about 50:50.

Damn those Weber passage plugs!

 This is unbelievable. The 1-2 carb came back from Pierce and  while David was installing it, he took a moment to closely examine the other carbs. Shockingly, the 3-4 is also missing a plug! It's an easy fix and hopefully this fixes all the fouling problems!

Smoking gun found in the carb?

 Pierce had the carburetor for a while now. Everything seemed normal on the flow bench. After a lot of back and forth, they finally did find something.

"In my 41 years of servicing Webers, I've never seen this problem."

Apparently there were 2 missing passage plugs which prevented a vacuum being drawn in the idle circuit. When he "back fed" the idle circuit, the problem became evident.

I remember I was consistently fouling a plug as well so maybe this has been an issue for a long time.