Is there a way to confirm leaking well plugs without removing the carb? I've got 2 old Q-jets that are running okay, but seem to have issues coming off the idle circuit when cold.
The early, 66-67 quadrajets had issues with leaking well plugs. They can be repaired and sealed to prevent leaking. In the 70's the design was better and not as much of a problem. If they leak significantly, you can have a rich condition at idle. The bowl can also drain after sitting and require you to crank the engine so the fuel pump can refill the bowl before it can start.
Most rear plugs that leak just "seep", and don't usually create running issues. When the plugs under the primary jets leak, they can cause running issues if they are leaking bad enough, but they too usually just seep and drain some fuel into the intake after shut-down. The best way to test them is to take carb apart and apply some soap/water mix to the plugs, then some compressed air to the holes on the bottom of the fuel bowl. This method will find the smallest leak and far more effective than any other method that I know of.....Cliff