Your carburetor (1973 Buick) should NOT have any upper idle airbleeds in the airhorn, they should be just above the idle down channel restrictions in the main casting.
Basic rules for idle airbleeds. All q-jets have lower idle airbleeds in the main casting.
There will be one pair of upper idle airbleeds, in one of two locations, not both.
After 1975, they will be in the main casting for all models, just above the idle downchannel restrictions, haven't seen an exception to this aside for Marine units or Service Replacment carbs for older units.
Until apprx 1970, most models will have the upper idle airbleeds in the airhorn, with a few exceptions.
Between 1970 and 1975, it we saw both styles, Chevy's using main casting upper idle airbleeds, and Pontiac having them in the airhorn, for example.
Here's the bottom line on the upper idle airbleeds, if you see 4 holes in your airhorn inside the choke housing, two of those holes are going to be upper idle airbleeds. They will be the pair closest to the front of the housing.
If you look in and only see two holes, those will be main airbleeds, and will directly above the main fuel supply passages to the boosters, when the airhorn is placed on the main casting.
We see some mixing a matching of airhorns, and a high percentage of commercially "remanufactured" carburetors may have blocked of one pair of the upper idle airbleeds, in attempts to produce a "generic" carburetor.
Some well meaning carb builders also mix and match parts, which can also produce a carb with two pairs of upper idle airbleeds, although that particular carburetor is NOT going to work well.
