Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Rough and High Idle after WOT

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droseberry:
Just bought a '74 Chevy K20 with a virgin 350.  Last weekend, I rebuilt the carburetor (Rochester Quadrajet 4MV # 7044513) because of hesitation during WOT.  Turned out the accelerator pump was old and cracked.  The carb works great on the truck now, got the idle adjustment screws tuned in and idle speed set perfectly.  My problem is when I go WOT.  The carb performs great at WOT however 9 times out of 10, I get a very rough idle right afterwards and after bliping the throttle back to WOT, it idles high until I blip the throttle to WOT a couple more times and then it goes back to normal.

I replaced the vacuum lines and ensured that the throttle plates arent sticking with the engine off.  I am baffled as to what could be causing this.  Any suggestions?

Cliff Ruggles:
Secondary throttle plates may be sticking open slightly and not returning to their full seat position....Cliff

droseberry:
Thank you for your response Cliff.  Would you suggest adjusting the tension spring?  Is there a proper method of doing this?

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