Quadrajet 7045213 idling and idle screw issue

[ryan72k10]

This carb is installed on 72 CHEVY K10.  Truck will idle in park or neutral.

1) I am not seeing much change change in my idle screw.  Is that because I have my air/fuel screwed in to far restricting fuel?   I was reading around 14” of vacuumon the gauge.

2) When coming to stop and holding the brake truck is wanting to die in drive or reverse.  If I slightly rest my foot on the gas pedal it will keep running, seems to be starving for gas, is this related to my air/fuel screws to far in restricting fuel?

3) What causes the fast idle cam arm to drop?  It seems when the arm doesn’t drop and u try to start the truck the next time the choke plate will not be closed causing a difficult start.

Any help is appreciated.  Just trying to learn more about quadrajets.

[Cliff Ruggles]

Those are divorced choke, choke on the intake with a link up to the carb.  Check the choke coil, link and make sure it's hooked up and pulling the choke closed on a cold start.  The heat from the intake manifold crossover opens the choke, check that as well.

Before you do any more with the carb check the distributor to make sure the timing is ROCK SOLID at idle speed.  Most stalling out when placed in gear is the result of timing falling off some due to wear in the distributor or someone installed one of those POS weight/spring kits at some point. 

Once you rule out timing, set it to spec (assuming stock engine) and adjust the speed and idle mixture screws for best idle quality and highest vacuum a the leanest settings. 

That's basically just turning the idle mixture screws in till the engine slows slightly, then back till it just idles the best.......