Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Two QJ's into one

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Cliff Ruggles:
At light throttle openings and light engine load the vacuum advance will be fully applied, so it will be adding all the timing from the unit for best MPG's......Cliff

F250 Restorer:
I was amazed by my results.  I've been monitoring my fuel consumption closely after doing Cliff's tip in method for the APT tuning.  It stayed the same for 4 tanks.  Then I thought I would richen up the mix and see if I got better power.  I turned the APT 180* counter clock wise, moving the m.rods up out of the jets slightly.  I was quite surprised to find that I drove 20 less miles on ten gallons of gas than before.  Ten miles less per 90*.  That is how sensitive the adjustment is!

Cliff Ruggles:
Absolutely.  Those metering rods have a slight taper on the upper section, from .044" down to about .042", then quickly on down to the .026" tips.  You will find a point in the adjustment range where very small movements of the APT screw will have a MAJOR impact on fuel delivery......Cliff

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