Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: Shark Racer on June 29, 2013, 09:42:26 PM

Title: 17058250 QuadraJet will not idle below 925 RPM
Post by: Shark Racer on June 29, 2013, 09:42:26 PM
So, I rebuilt this QuadraJet about 2 months ago using one of Cliff's kits, set up to his spec.

73/44 with DA secondaries.
70/70 main bleeds.
Float 1/4"

036 idle tubes, 046 idle DCRs.

Vehicle is a 67 Firebird 400 with auto.

All vacuum sources were capped, could not get the warm idle to drop below 925. We verified we were on the idle stop screw and fast idle was disengaged. (Fast idle is ~1300 rpm).

I pulled the throttle body tonight and the throttle blades are pretty even, ranging from maybe 2-5 thousands clearance around the blades. I would say that I think they're a little "open" compared to other Q-Jets I've seen, but not incredibly so.

Any thoughts?
Title: Re: 17058250 QuadraJet will not idle below 925 RPM
Post by: Shark Racer on June 29, 2013, 10:13:20 PM
No idle bypass air, FWIW.
Title: Re: 17058250 QuadraJet will not idle below 925 RPM
Post by: Cliff Ruggles on July 02, 2013, 04:42:09 AM
The air to sustain that high of an idle speed has to come from someplace?  The secondary throttle plates must be tightly closed/sealed up at idle.  Make sure there is some slack in the link that applies them and it's not holding them open slightly.  I see this a lot, and get them in here with poorly indexed/centered secondary throttle plates as well....Cliff