I started attending factory schools on Q-jets a year or so after they were introduced. After some growing pains with an oddball inlet needle valve design the first year of production, they became one of the best-engineered carbs on the market. It is essential that you make all the adjustments specified, in the right order, as you rebuild one. There are literally hundreds of different calibrations for specific engines, so be sure the carb you have was designed for the engine it's on. Part number matching to the application is critical. The best Q-jets are probably the early 1980's models just before they went to electronic mixture control. Those carbs have the benefit of almost 20 years of production to get all the bugs worked out.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!