(Pt 2) Possibly OT, ??s about a GM feedback Q-jet

[The Punisher]

If you are opening up the throttle blades too much to idle you may need to 
drill a small hole in the butterfly near the idle port. You dont want to 
expose too much of the transfer slot. and you NEVER want to be above the 
transfer slaot at idle. That will throw off the whole idle circuit to main 
circuit transition, and you will have a horrible stumble as well as bad 
run-on.
The "idle screws" dont realy adjust the mixture, just the volume of 
emulsified fuel/air going through the idle circuit. This then will mix with 
the volume of air going around the throttle blades. get youre throttle 
blades to close down more, and adjust the "mixture" with the idle 
jet(recomended) itself and the idle air bleed (not recomended cuz bigger is 
leaner, but comes on later).

Drilling a small hole (1/16 of an inch or so) can usualy improve things a 
whole lot.





>I failed to mention that setting these carburetors has always seemed a 
>matter of
>reverse tuning to me.  Opening the idle screws adds more fuel, so the 
>engine runs
>better.  Increasing timing makes the engine run better still.  Problem is 
>that the
>idle speed ends up around 1000-1500 when the engine really starts to smooth 
>out.
>Been down this road enough times to take home a couple of tee-shirts.
>
>Instead of opening the idle screws until the engine runs well, it always 
>seems to
>work better to open the throttle adjustment until I start to get vacuum on 
>the
>ported vacuum line to the distributor.  With the timing set to factory 
>specs, the
>idle mixture screws can be adjusted to obtain the best (not always good) 
>idle.
>This usually leaves the engine idling at reasonable speeds in and out of 
>gear, and
>runs reasonably well.  Sometimes the throttle plates need to be opened 
>slightly
>more, but this can lead to high idle on fast decel if the vacuum advance is

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