Well, I think I understand your question.
The Q-jet has 4 metering rods. Two are inside the carb under the top lid, they are for the primarys, the front 2, small butterflys. They adjust up and down by engine vacuum to richen the mix during acceleration, and then lower down some during cruise.
The other 2 are for the rear 2 big secondary butterflys. They also move up in the jet when the secondarys are opened.
Both the front and rear rods are replacable. The front rods fit into replacable jets, the rears go into a fixed hole.
You can change the front ones to smaller diameter rods ( more jet area, richer mixture) or bigger rods, ( smaller jet area, leaner mixture.) You can also change the jets too.
You can also change the rear rods for a richer or leaner "wide open throttle" position.