Those jets should be numbered.
Carburetor model B, BC, BV, 2G,2GC,4G,4GC are all in the group "A" jets. In this group are three different styles, a 90 degree square cut, a 60 degree approach angle short taper, and a 60 degree approach angle long taper. All three will interchange, just stay in the same sub group. Each jet is stamped with the orifice diameter, which may or may not be the true diameter of the hole. But a decrease in numbers will decrease the size, same for going larger.
By looking in the top side of the jet, you can see the difference in the three styles. Going from the largest hole in the jet to the actual jet orifice, the angle and length of the taper cut is the difference, it effects the fuel flow through them
Joe
