Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
90% of 'Carburetor Problems' are 'Ignition Problems'
Buick73:
--- Quote from: mcx on January 07, 2026, 03:35:59 AM ---…looks like the wrong carb…every 7042240 I’ve built does not have that early style air lid…1972 455 also have a slash cut vent tube…pix#4 seems to show the secondary air valve linkage might be incorrectly adjusted….also check the front dashpot and verify it is functional.
--- End quote ---
The carb is indeed stamped with the '7042240'. As I recall, the top has been replaced at some point in the distant past. Yes, I know the secondary linkage is weirdly bent. (The problem was that it was dragging the choke mechanism). It's not perfectly angled, but it does work as intended- pulls the secondaries shut at high vacuum, dashpot fully releases in about 2 seconds, & secondary air valves open.
Buick73:
So, I understand that people are divided on rather the Pertronix is a 'good thing' or a 'bad thing'. But my original question was about the hesitation issue (please see original posts).
mcx:
--- Quote from: Buick73 on January 10, 2026, 12:07:53 PM ---The carb is indeed stamped with the '7042240'. As I recall, the top has been replaced at some point in the distant past. Yes, I know the secondary linkage is weirdly bent. (The problem was that it was dragging the choke mechanism). It's not perfectly angled, but it does work as intended- pulls the secondaries shut at high vacuum, dashpot fully releases in about 2 seconds, & secondary air valves open.
--- End quote ---
…check the replaced air lid and verify it wasn’t replaced with the Buick 750cfm version, as those have the upper idle air bleeds in the air lid….the 800cfm version(7042240) do not have them in the air lid (unless custom modified)….Good luck.
Buick73:
--- Quote from: mcx on January 10, 2026, 05:13:26 PM ---…check the replaced air lid and verify it wasn’t replaced with the Buick 750cfm version, as those have the upper idle air bleeds in the air lid….the 800cfm version(7042240) do not have them in the air lid (unless custom modified)….Good luck.
--- End quote ---
What would that do?
Please see picture.
mcx:
….open the choke door and look into the primary side….if you see only the two main air bleeds it is “factory”correct, if there are four( 2 main plus 2 idle air bleeds it is not “factory” correct….post a picture of the primary side with the choke open.
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