Why is one carb drawing less air

[grasshopper]

Hi all. Im having an issue with my 40 idf's. Im using a synchrometer on them to set them up. The throat closest to firewall draws slightly less air. Can I use my air bypass screws to fine tune it ? Also,just wondering, when screwing the fuel mixture screws in or out, what is the preferred setting? I've read that they should be aprox 1.5 turns out. By this does it mean one full 365 degree turn out of the screwdriver and half more or is half a screwdriver turn considered one turn ? I hope this makes sense,,lol Any help would be appreciated thanks.

[rebar1111]

One and one half turns is 360 +180 deg on the screw driver.