Jerry - you aren't old enough to remember LOL

Schebler (and others) had the air valve in the 'teens (the 19 teens).

The early 4GC's did not have the air valve; from memory, 1956 was the first year, and too lazy to look it up.

Jon

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop