Big Ed covered most of the variables, trying to make the point that every setup has different sensitivities. What you didn't cover is changes in the fuel head under a "g" load. I've had some high performance planes that an 1/8" change in the tank height made the difference between leaning out in turns and killing the plug, to going from lean to rich. Other mild sport aircraft much less so, but when I configure a plane, I expect the engine to run the same regardless of orientation. Properly setting up the fuel tank position relative to the carburetor is part of this process.