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Idle issues


New member
Nov 5, 2013
1981 Red Coupe
So i have searched every forum imaginable and keep finding threads that sound promising but don’t have my symptoms.

About the car:
81 350, quadrajet carb, edelbrock intake, vortec heads, comp 12-422-8 cam, roller valvetrain, 1.5 rockers, long tube headers, true duals, initial timing is ~10-12* btdc, all emissions stuff removed (air pump/egr/etc), ac removed.

all unused vac ports on the carb have been capped, really the only one still used is for the choke.

cold high idle is fine, i need to adjust the choke spring as I live in VA and not the northeast. Normal idle in park/neutral is 900-1000, in drive it drops to 7-800 and is steady. Sticker oncthe hood says 600 in neutral and 500 in drive. With my cam I’m not sure thats feasible...

once driving and its more than hot, i put it in park and the rpms go to the 900-1000 mark, then slowly creeps to 1200/1300/1400rpm.

Mixture screws are about 2.5 out, iab is around 4, i dont remember what the mixture control solenoid screw is put to (but i found a cliff ruggles book and thread and It was rebuilt to that ...i think 4-6 from bottom)

what would cause the rpm creep in park/neutral??? Strictly a vac leak or a mix between vac and carb settings?
Last edited:
do a search for high idle on this forum from May 2019..it may be what your looking for.
good luck!
do a search for high idle on this forum from May 2019..it may be what your looking for.
good luck!
Bill, I saw that thread about the choke tuning - but since this occurs when hot the choke shouldn't even be applied once fully warm?

As a matter of fact, just to make sure it wasnt playing games with my hot idle I moved it and nothing changed.
I have heard of several people in my area,who have had issues with there quadrajets adusting these jets and had success doing it.
the fact that your has been altered may have something to do with it.
its a suggestion thats all.
Is the choke coil operating properly. They will poop the bed and wired intermittent stuff will happen. Replace the choke coil they are cheap.

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