[Kenth]

Thank´s for sharing you info Tom V!
In Delco Rochester Bulletin 9C-640 Date December, 1965 #7015106 throttle body gasket (vented) is used for the outer carbs as well as the center cab.
But, in Delco Rochester Bulletin 9C-627 Date May, 1967 (Replaces 9C-640, April, 1966) throttle body gasket #7015345 (not vented) is used.

I have found my 1966 Tripower GTO starts easier hot with the vented 7015106 gasket, but i´m currently using the closed throttle body gasket per the manual.
What was the reason for the change over to the closed gasket?

And, i have not found info for the direct reason on the .030" drilled holes in 1964-66 outer carbs throttle blades, other than keeping the throttle bore clean from "gumming up"?

Looking forward for your info on the center carbs!