<VV> Carter YH Trivia Question

[grant young]

Just wondering if anyone knows why GM had the bowl cover vents in the
Corvair version of the Carter YH carb blocked (with a ball bearing)? This
vent is open in the earlier Nash and Corvette versions of the same carb
(thus the different part number). I have a feeling that this could
contribute to the fuel drip problems in the early Corvair carbs, but not
sure, and would like other opinions (and to know if anyone has ever removed
one to try it out). JC Whitney once sold a top venting kit that
circumvented the blockage.
Thanks
The Carbmeister