Different types of carburetors handle the idle mixture control in different ways.

The Rochester B screw is located after the air and fuel are mixed, thus CW (in) is leaner, because CW reduces the volume.

Other carburetors (many older Zenith and some Strombergs) meter air with the screw rather than the mixture of fuel and air. In this case, CW (in) is richer because it reduces the amount of air.

And then you have the strange case of the two-barrel Schebler, which uses knobs instead of screws for the idle adjustment. One is right-hand thread, the other left-hand thread. Thus using one CW is richer, the other CW is leaner.

Rather than read what has been written, sometimes in error, on the internet; always best to look at the idle circuit on the carburetor in question. Easy to tell by looking how it is going to work.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
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The Carburetor Shop