It doesn't take much.
100 years ago, the carburetor companies specified a FUEL level (not a float level) at a specific pressure WITH A SPECIFIC ORIFICE FUEL VALVE SEAT.
Somewhere along the line "mechanics" got too cheap to buy the correct tools, and/or to lazy to make them.
Also, 100 years ago, Stromberg (and probably others) actually specified different orifice valve seats, depending on the distance from the carburetor to the fuel feed (gravity feed).
Many of our customers place carburetors on a different engine, or live at high altitude, and call us for jetting recommendations. We always tell them to build the carburetor stock; then adjust the fuel level in the bowl by 1/32 of an inch; as this change will approximate 1 jet size. This way, an enthusiast can do preliminary testing WITHOUT having to buy as many different jets.
The corollary to this test is how critical using correct parts, and correctly adjusting the float setting is to an engine running correctly under normal conditions.
Jon
