The first Quadrajet carbs that I went to school on in the mid-1960's had small brass primary metering rods that just hung loosely in the jets. After a few thousand miles they started running rich. We found the metering rods worn undersize, and egg-shaped, oversize holes in the jets, caused by the swirling action of the fuel flushing through them and the rods rattling around. Rochester solved the problem by adding a small tension spring to the metering rod holder that made the rods drag the sides of the holes and stop free-floating.
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!