Carbking doesn't answer PM's; because every forum is different, and he is computer-challenged :o
As a general rule, most carburetors were calibrated as follows:
Sea level~4000 feet - standard calibration
4000~6000 feet - one size lean
6000~7000 feet - two sizes lean
7000~8000 feet - three sizes lean
Some carburetors were specifically calibrated for 10000 feet and above; but these are best left at those altitudes.
Easiest procedure is to locate the identification number for the carb in question:
Carburetor identification guide Then one can look up the specifications for that carburetor at one's current altitude. Most of these units have a fixed jet that has no adjustment; one just installs the correct jet.
Jon.