Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

7041540 Buick 455 goes lean at WOT

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Rhett:
It was a 6211 800 CFM. And a leaky, uncalibrated POS that wouldnt idle too

lightning boy:
looks like it's too fat to me. What makes you think it's lean?

Rhett:
It should be fat, way fat but doesnt act like it. plugs, tailpipe, smell all normal if not slightly lean. The thing that concerns me is with the Q-Jet the fuel GPM went backward, and the HP levelled off where as with the Holley it kept climbing. Yeah the 02 sensor shows lean at WOT, but cant count on that cause its too far back in the system to be entirely accurate. I have another 540 that has a stock bypass, 76/44's and .067/.070 idle bleeds and .052 ICR and it wont idle at all on this engine. It likes the bypass, but I always suspected too much bypass is contributing to a lean condition. I keep thinking a .135 needle/seat was causing the fuel turbulance/stand off at high volumes, but a .145 and a .152 seat didnt change the condition.

Kenth:
This is what i would have started with:

Fuel Inlet   0.135"
Float Level   13/32"
Idle Tube   0.039"-0.040"
Idle Channel Restriction   0.062"-0.064"
Accel Pump Discharge   0.033
Main Air Bleed (upper)   0.069
Main Air Bleed (lower)   0.039
Idle Air Bleed (upper)   0.054
Idle Air Bleed (lower)   0.080
Mixture Hole   0.095"-0.100"
Primary Jets   0.074
Primary Rods   0.045
Secondary Well restriction   0.039
Secondary POE Restriction   0.059
Secondary Tube Restriction   0.036
Secondary Rods   0.0527 CV
Secondary Valve Opening   1.287
Secondary Hanger   F
Idle Air bypass   0.110"

JMHO

Rhett:
Well I can still set the other 540 up that way and see how it likes it..

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