Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Need help with recipe #1 No Idle

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mrk3cobra:
You can see from my post that I changed the float level to 1/4".
The float is new and is the smaller size.
I did not change any shaft bushings.There is no play in the shaft.

I followed the recipe exactly my guess is there is something wrong internally with the carb.
I know the throttle plates are not closed because if I cover part of the intake of the carb I can lower the idle screw and the ported vacuum ports work like they should.And when I do this I can increase the vacuum from 11" to 15".....

There must be a major leak in the carb...

Cliff Ruggles:
No play at the shaft doesn't mean that it isn't sucking a ton of air by the shafts.  If you were to remove the shaft and gauge the bore and the measure the shaft, you will find it has considerable side play.  The factory tolerance was too much for my liking, so we install bushings in all units built here.

You have a lean condition, and need to add more idle fuel.  The .078" lower idle airbleed comprimises the "recipe" considerably.  I would resize it to .070", and open up the idle tubes a couple thousanths, and take the idle down channels to .052-.055".  You will see an immediate improvment.  If not, you have a big air leak someplace, either by the shaft(s) or throttle plates aren't fully seated at idle (common problem)....Cliff

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