This is an excerpt from "Rochester Carburetors by Doug Roe"- Idle System
"Idle Systems-Do no alter the idle system unless off-idle or light-throttle acceleration sages exist. Nearly any modification made here will affect the engine's ability to pass emissions inspections.
The channel-restriction orifices can be easily altered if you have a suitable set of small drills. The only reason to do this is if light throttle weakness and surge exist. Increasing the diameter a few thousandths of an inch will richen the off idle misture. Never exceed a 10% increase in orifice area. Use tacky grease ion the bit to collect tiny chips as you drill the thing orifice. A 10% increaes in channel restriction orifice area is equivalent to approx. a .003 in. increase in orifice diamter.
Q-jet idle tubes are difficult to alter. Their diameter is .03-.035 in. and standard drill bits that size are approximately 1 1/2in long. The tube orfice is 1-21/32in. below the tubes top. The bit will not reach the calibrated orifice and enlarging the upper portion of the tubes does not help. Extral long drills in the required size range are difficult to find. Idle tubes are literally impossible to remove without a special tool. And, these tools and parts are not dealer service items, so don't expect help from your regular parts man or service manager. ........
There are two reasons why you might want to increase the idle tube orifice size. First, when the curb idle is not satisfactory with the idle mixture needles turned out (counterclockwise), larger idle tubes will give more mixture control. Second Qjets are sometimes palgued with nozzel drip at idle, which causes poor idle stability....................
Should you enlarge the orifices, be sure to get all the chips out. Remove the primary jets and force fuel and air back and forth throught the idle tube via the het wells. When enlarging the orifices, o no exceed the stock diamter by more than .00d in."
read: its going to take some effort to get it to idle, wether you want to ditch the carb for an aftermarket one is up to you. If you want to stick with the Qjet, the article above tells you where to start.
good luck
