Carter produced 128 different models of the W-1 carburetor, many of them used by Chevrolet (1932-1949). The 1937 and newer are very good units.

The YF came later (1950), and was slightly more technilogically advanced.

The major difference as important to the enthusiast (thanks to ethanol), is the composition of the accelerator pumps. The W-1 pump is leather (totally impervious to ethanol). The YF uses a neopreme diaphragm, which holds up well in daily drivers, but tends to crack over time for vehicles which are not driven often. For a daily driver (or a vehicle for which the owner can acquire genuine gasoline) the YF remains an excellent choice.

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