I just got my qjet installed and running...took a trip to providence (90 mile round trip) tonight. I am VERY happy with it so far.
The only problem i am having is the idle circuit. I have the idle screws out about 2 turns, its pulling about 19-20" vac, but its idling at 900-1000. The throttle stop screw is backed off all the way and the butterflies are closing OK. If I turn the idle screws in another 1/2 turn it starts stumbling and the vacuum drops to 15-16. Any ideas? I have worked on lots of carbs of all kinds and never had this type of problem on a fresh rebuild like this.
Also, what is the device in the right front corner of the carb in the main body that looks like a circular float with a metering rod sticking out the bottom? Is this for the power circuit or some kind of altitude compensator? I took it apart to clean it, and reassembled with (roughly) the same number of turns. There is a brass freeze plug over it which can be removed apparently to adjust this circuit while its running(?) Could this be related to my idle problem?
Should i remove the plug and install a pipe plug so i can adjust this?

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1984 Z28 (L69) monochrome tangerine orange with IROC decals and hood
1987 IROC wheels with Goodyear GSC's
305 from 87 IROC with 1994 LT1 cam (203/208 .450/.460")
performer intake with holley 600 (#1850)
Qjet is in the works
dynomax cat-back
non WC T-5 with 0.73 5th
3.27 nine-bolt