Monojets are a maligned carb around here, they are a metering rod type carb, and sometimes need both jet and rod resizing to get the desired results. Just changing the jet will affect both the power and the cruise circuits. Changing the rod alone will only affect the cruise stage only as all the rods have a common diameter on the power portion of their shank.
Doug Roe has an excellant Rochester Carb book ( an HP publication) that still shows up at Amazon-get it. Roe was a Rochester engineer and he has a few pages on modifing the monojet which is of the same design family as the quadrajet. Roe has tips on modifing the power piston spring tension, the adjustible part throttle jetting as well as simply changing the main jet/metering rod. I had a mono on a '69 230 motor and was able to turn it into a really nice mannered standard shift carb (meaning you can monitor carb performance more easily with a stick than with an automatic with its masking torque converter action.
