Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Should I ditch my current carb on my Pontiac 301 powered 79 Trans Am?

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Ponchonutty:

--- Quote from: Mudsport96 on September 13, 2025, 05:49:55 AM ---What do you mean crappy when you floor it? Backfire? Falls on its face? No acceleration?

--- End quote ---

Has a slight miss at idle.  When I floor it it completely falls on it's face.  If I back out of the throttle a bit it will run better and then shift through the gears.  My wideband I has to be off since when I floor it, it will peg at 50.  I hear no pinging.  Actually through most of the rpms it shows its running extremely lean.

Ponchonutty:
Got another carb off of a 75 pontiac.  Didn't change a thing in how it behaved.  Buddy is thinking there's a severe leak somewhere but is unsure.  Said he will be smoking the engine and look for leaks.  He thought possibly the valley pan gasket?  That's possible I assume since I have never had it off but I know prior to me owning it, someone has rebuilt or at least gone through the engine.  Had another comment saying to check the cruise control vacuum but if it was leaking from that, wouldn't the cruise fail to work?  I am not certain the wideband is accurate at this moment because when it pegs at 50 during WOT shouldn't I hear severe pinging?  This is the wideband I am using.  Yes, I have calibrated it several times too.  If you squirt starting fluid down the carb while at idle the engine will smooth out and the wideband will go around 12-14 where it should be.
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