Carter Thermoquads ~ 'More General Information'

I just noticed, on early 69-71 CS TQ carbs, primary metering rods go directly into the main well, through a vertical passage directly above the jet, the jet is screwed into the lid at bottom of main well- main jet, metering rod, main well all share same stanchion/passage in direct vertical line.
fuel goes past the metering rod directly into the primary discharge tube nozzle, in the booster venturi.
this means, the space around the primary metering rods in the early CS TQ carbs, also serves as an additional air bleed for the primaries. the metering rod guide hole is brass bushed just like an air bleed, to get the proper size- unlike the 72-up carbs, where the metering rod guide holes are just drilled through the aluminum.
The metering rods at that point are .073", the rod guide hole is .076". there's a tad more primary high speed air bleed area there at the interface, no doubt factored in by the engineers back in the day. add that to the primary air bleed tube size of .028" - total high speed air bleed is darn close to .030" then, just like a Holley 4 bbl.