Plugs fouling

[VW911]

I am running a 1641cc motor
009
high-rev points
Bosch wires
dual 40mm Kadrons
041 mexican heads
Thunderbird exhaust

I am fuel fouling plugs #1 and #3 ?????
I can not fiqure out why. It would make more sense if it was plus 1&2 or 3&4 being one carb is feeding one side. Everytime I put in new plugs it fouls them in one day. I pull the wires while the motor is running and no change in idel speed on 1 & 3. I put in new plugs then change the wires to see if it was the wires but no change, 1 & 3 fouls out.

Anybody have any ideas what could be causing this???