If you really want to see what your carb is doing or not doing, ie a flat spot off idle invest in a hand held wideband. They are dirt cheap these days and besides drilling the downpipe and welding on a bung, will tell you what exactly your air fuel is doing in real time. No reason why one of these isnt in everybody's tool box to take the guess work out of carb tuning.
1953 Chevrolet 3100261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY GalleryVideo of the 261 running1964 GMC 1000305 Big Block V6, sm420, the next cab off restoration
