Author Topic: High idle, cant get it down  (Read 1765 times)

Offline cj7

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High idle, cant get it down
« on: June 14, 2018, 12:10:00 PM »
I've got a 70s quadrajet that I rebuilt with the SR kit. and replaced both bushings, there doesn't seem to warpage when i checked with a straight edge and the manual choke does kick down. but for the life of me i can not get it to idle down. when it starts up cold its at about 900 ( I don't really use choke because i live in California) and when its warm its at about 1100 RPM. ive adjusted the idle screw to the point where it is no longer in contact with the throttle bracket. I cant seem to find a vacuum leak, but other than the high idle, it runs PERFECT. one thing i did notice is that there is the smallest gap in the sides of the butterflys by the shafts that i cant get rid of. any help would be appreciated.

Offline cj7

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Re: High idle, cant get it down
« Reply #1 on: June 14, 2018, 12:33:36 PM »
Ive also tried cleaning the idle tubes with a small drill bit and compressor

Offline carmantx

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Re: High idle, cant get it down
« Reply #2 on: June 14, 2018, 06:10:52 PM »
What carburetor, and engine specs?
You may have too much bypass air.
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Offline von

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Re: High idle, cant get it down
« Reply #3 on: June 15, 2018, 02:23:48 AM »
Make sure there are no vacuum leaks at the carb and elsewhere. Also make sure the secondary throttle blades are closing all the way. There should be "slop" in the linkage rod on the driver side between primaries and secondaries with engine off. If tight it could hold the secondary blades open a tad at idle. Make sure the ignition timing isn't too high at idle.

Offline Dogmeister

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Re: High idle, cant get it down
« Reply #4 on: June 15, 2018, 09:43:37 AM »
You might try loosening (not removing) the screws holding the primary blades to the shaft, let them seat (choke full open, idle screw off its stop) and re-tighten. Probably should do the same with the secondaries. Also check your ignition timing. Could be too much advance. I've heard of the centrifugal weights not retracting fully due to weak springs and causing idle issues.

Offline cj7

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Re: High idle, cant get it down
« Reply #5 on: June 28, 2018, 02:38:43 PM »
Thanks for the replies, I have a stock chevy 350 with Vortec heads. There is slack in the secondary connector linkage and does appear to close all the way. I will double check my timing, but last time I checked it was about 10 or 12 degrees without vacuum advance. But regarding reseating the blades, I used red loctite as stated in the instructions for the screws. how do i go about loosening the blades with loctite on them without breaking things?

Offline 77cruiser

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Re: High idle, cant get it down
« Reply #6 on: June 28, 2018, 02:50:48 PM »
If they don't come loose a little heat will do it.
Jim