I believe so.

I think it was to work with the idle circuit mixture. they are almost right above where the bleed needles come out.

Also -
I would imagine that you would want the butterflies completely shut at idle and without the holes you would not have any bleed air for the idle circuit.

Bill

Got me a NEW Project
1970 GTX 440+6, 4 spd, 4.10 Dana and N96 FE5 (top/bottom) and black bucket interior.
Original transmission and Dana - Engine is a service replacement block.

Body has all stamped #s + VIN/TRIM tag and door sticker. Been hunting like all hell to find the Build Sheet.

garage find, only had 41,850 miles on ODO.