Cliff's Quadrajet Parts and Rebuild Kits
General Category => Quadrajet Carb Talk and Tips => Topic started by: Turbo26T on February 17, 2026, 12:54:57 PM
-
My project car will have A/C.. Im looking for an idle-speed solenoid for my Quadrajet with enough force to open the throttle at idle when the compressor comes on .Factory Q/Jet idle stop solenoids only extend after the throttle is opened and do not have enough force . This would lead to stalling unless you blip the throttle.
Any thoughts , real world examples ,SWAG's etc..
Thanks ,
Stan
-
It would help knowing the carb-# and application.
-
Kenth : Its a #17082224 ..but I've tried factory Q/Jet idle-stop/idle-speed solenoids and they are not strong enough to open the throttle from curb idle . ..Only after the throttle is opened , will the factory solenoid extend and hold idle speed at an increased RPM. As I understand it , they were used to retract after the ign is turned off to completely close the throttle plates to negate "Dieseling"
What I'm looking for is a solenoid that has enough force to increase idle speed when the A/C compressor comes on without having to blip the throttle pedal...Either a vacuum or an electric (12V) solenoid can be made to work..
Hopefully this may clarify what I'm trying to accomplish..
Stan
-
Normally, the idle speed is set with the solenoid active, A/T gear engaged and AC on.
No further increase in speed for AC on should be necessary.
With the solenoid inactive, the speed is set 100-150 rpm lower.
-
Kenth : Thanks for your input...I , however , am well versed in solenoid operation in regards to throtte speed increase ..No offense intended , but Im not wanting to know how they operate , setting procedure , wiring diagrams , etc
I am simply looking for a solenoid strong enough to open the throtte against the return spring pressure and increase the RPM's when the A/T is in gear , when the A/C compressor comes on @ Idle....
Thanks again for your input
Stan
-
I acknowledge this is an old thread but I have a solution for which I did a video posted on YouTube:
Classic car AC idle compensation options (https://youtu.be/JFhQKXpx-1M)
Hope this helps.
-
Zucchi : Thanks for the reply..I had viewed your videos while researching a solution to my idle speed issue.. What I found was that those parts are long since discontinued
What I came up with is a 12v vacuum solenoid valve ( Omega Enviro Tech P/N 29-40000) that opens to sends manifold vacuum to a carb mounted vacuum dashpot( Guaranteed Parts P/N 779-269 , Rochester 7044055).. The dashpot is strong enough to overcome throttle spring pressure to increase idle speed ...When the AC cycles on 12V is sent to vac switch , that opens and routes manifold vacuum to dashpot increasing idle speed without having to blip the throttle....I had to custom make the dashpot to carb mount plate.
I tried to post pictures of the setup , but I dont know how to do that and could not get them to post
Stan
-
I'm glad to hear you devised a solution. I would like to see photos. I tried using the "Insert Image" button then insert the http address of the image but that didn't work.
Posting a link works…
https://drive.google.com/file/d/1JhEweHVQeCu4oqndJaPeR4skeX9ry-sM/view?usp=sharing
Uploading the image seems to work too.
Albeit some of the parts I listed in the video's description are discontinued, a couple of the TCS valves are reproduced and sold by restoration suppliers. Nevertheless, despite them being discontinued, it doesn't mean they are unobtainable.