This is what caught my attention about this
ORIGINAL: Flyboy Dave
If you are setting the low speed needle this close to the spraybar at WOT, you
are using it to regulate the fuel flow, as you would with a forward mounted main
needle. Your high and low speed settings are out of balance, and you are blocking
the nozzle with the low speed "plug".
In other words, you are setting the "high speed"....with the "low speed'.
FBD.
You are right.
MB.