Quadrajet carbs

Swapping jets and rods on a quadrajet creates different sizes. To calculate the size of the opening use this formula.

jet ID X jet ID X.7854 gives you area in sq inches. rod OD X rod OD X .7854 also gives you area in square inches. Here is a example... lets just say we have a .050 rod and a .100 jet,

.050 X .050 X .7854 = .0019635 sq inches.
.100 X .100 X .7854 = .0078540 sq inches.
Now subtract the rod area from the jet area. In this case it is .0058905 sq in area. The equivalent effective area in this example would be a .0865 hole size,

.0865 X .0865 X .7854 = .0058766 (close enough?)

This formula will work but since all primary rods are .016 at the tip at WOT it will calculate that you need to drop 5 jet sizes to stay about the same area if you are planning to run without rods. You can remove the power piston spring allowing the rods to drop into the larger taper then figure the area.