Q-jet idle question
Thread Starter
Heel & Toe
Joined: Aug 2008
Posts: 16
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Q-jet idle question
Ever since I bought my 69 vette back in the 80's and even after a carb re-build in the 90's, the car idles around 1400 rpm unless I "kick it down" with the gas pedal (then it idles around 600 rpm). This happens whether the car is hot or cold. Is there a "simple" adjustment to this or is it just the way they are set-up from the factory? It doesn't really bother since it's been like this for so long, but who knows?
Specs: L-46 4-speed A/C 350/350 with stock engine and stock quadrajet carb.
Thanks in advance.
Specs: L-46 4-speed A/C 350/350 with stock engine and stock quadrajet carb.
Thanks in advance.
Advanced
Joined: May 2008
Posts: 55
Likes: 0
From: Bar Harbor Maine
First, make sure the choke if fully open when the engine if warmed up. If so, check for a sticky high idle mechanism on the choke side of the carb. If that's OK, see if you can manual close the throttle from the 1400RM - if so, then you probably have a weak throttle return spring, or a sticky spot on the throttle shaft.
Instructor
Joined: Jul 2008
Posts: 100
Likes: 0
From: Long Jetty NSW
Have you been able to establish whether it's the carb or the linkage/cable thats sticking? What happens if you disconnect the linkage/cable?
Some things to look for .............
Something fouling the throttle arms (vaccuum hoses etc)
Something fouling up under the dash, near the top of the accelerator pedal.
Is the choke cam not operating properly? (i.e. the choke is causing fast idle even when the engine is hot.)
Is it a cast iron "smiley" manifold with the exhaust passage in front of the primaries? Depending on gaskets/heat shield used, this can cause a problem, but generally only when hot.
Some things to look for .............
Something fouling the throttle arms (vaccuum hoses etc)
Something fouling up under the dash, near the top of the accelerator pedal.
Is the choke cam not operating properly? (i.e. the choke is causing fast idle even when the engine is hot.)
Is it a cast iron "smiley" manifold with the exhaust passage in front of the primaries? Depending on gaskets/heat shield used, this can cause a problem, but generally only when hot.
