CUTLASS 307 high idle at start up

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MrSony

Geezer
Nov 15, 2014
6,790
6,673
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Des Moines, Iowa
Once you've confirmed there are no vacuum leaks, this is the adjustment for the fast idle:
1. Car has to be overnight cold, or cold enough you can rest your hand on the engine and not feel a tickle of warmth
2. With the air cleaner removed, plug any vacuum ports
3. Fully depress the throttle once, the choke flap should snap shut and have a light tension to it
4. The picture shows the adjustment screw, loosening it lowers fast idle rpm, tightening it raises it. This screw is only effective when the choke is on, adjusting it with the engine warmed up does nothing, especially since the engine gains rpm as it warms up. 2000rpm cold will end up being 2500+ with a warm engine.
5. Adjust the screw to obtain whatever rpm is on the tune-up decal or emissions label. If none are present, go with about 1200-1500rpm. 2000rpm is too high.
6. Curb idle, or hot idle screw is on the drivers side of the carb and is only effective when the engine is hot.
CIMG1461 cropped.jpg
 
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chekmark

Not-quite-so-new-guy
Sep 19, 2022
23
29
13
Once you've confirmed there are no vacuum leaks, this is the adjustment for the fast idle:
1. Car has to be overnight cold, or cold enough you can rest your hand on the engine and not feel a tickle of warmth
2. With the air cleaner removed, plug any vacuum ports
3. Fully depress the throttle once, the choke flap should snap shut and have a light tension to it
4. The picture shows the adjustment screw, loosening it lowers fast idle rpm, tightening it raises it. This screw is only effective when the choke is on, adjusting it with the engine warmed up does nothing, especially since the engine gains rpm as it warms up. 2000rpm cold will end up being 2500+ with a warm engine.
5. Adjust the screw to obtain whatever rpm is on the tune-up decal or emissions label. If none are present, go with about 1200-1500rpm. 2000rpm is too high.
6. Curb idle, or hot idle screw is on the drivers side of the carb and is only effective when the engine is hot.
View attachment 211160
Great info, thanks for the help.
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
8,087
17,292
113
Follow the gm procedures. Engine warm. Fast idle adjustment screw on low step. Right there on the emission label.
 
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