Good job reworking the bowl vent rod spring.
Throw away that useless Chilton book and get the
real service manual. There is no specific number of turns the mixture needle should be adjusted to. Each and every individual carburetor, on each and every individual engine, will require a different adjustment. You need to go to
this thread and read how to set the idle mixture correctly. Also remember that the 1920 uses a foam (nitrophyll) float, which over time absorbs gasoline and grows heavier than it should be. When that happens, even the correct height adjustment won't cause it to work correctly. Best to install a new float; they are still available though no longer generally stocked at parts stores.