Yes, needle valves, thats some good work there Matt, missed that post when i was reading through. It was entirely possible there were other problems at play, back then i was tuning by the seat of my pants. I was using bp100 fuel, which may have complicated things for me. The idle and low rpm suffered alittle with the change, with a noticable float rock, loping increase at idle, which tended to cause fouling issues if left idling for too long, but at high rpm in 5th seemed to make a very good improvement. I assumed it was float bowl related due to the engine leaning up (kill plug checks) at max speed and not pulling, then backing off throttle slightly and pushing again increased rpm then fell off shortly after (possible throttle jet assist)?! Well it made an improvement for me, so i took the small victory over the Weber demons! lol
Also it was interesting to see the AFR readout of your needle valve experiment, showing what effect it actually had. Thanks.