Spark Plug Mystery

[LuvNLife]

My truck has a new (less than 300 miles) 350/260 crate motor. Just about everything on it's new. The mechanical fuel pump was putting out way too much pressure for the Edelbrock carb, so I know the plugs got fuel fouled. I've got a good pressure regulator on it now, and put a new set of plugs the other day; I'm running the "shorty" Accels, since access is limited with long tube headers. On the driver's side, sure enough, cylinders 1, 3, 5 and 7 were pretty black and sooty, but, on the passenger side, only 4 and 8 were. The plugs in 2 and 6 had almost white ceramics still.

Timing was at 12 degrees with full manifold vacuum, nowt reset up to 16 degrees. The truck runs good (for what it is), with no odd noises, no oil use, no water use, no missing, no smoke. I would think if I had 2 dead cylinders, I'd certainly feel it, so I'm stumped. Thoughts?

Jerry