Rochester Quadrajet primary metering rods are used to tailor primary part throttle air/fuel enrichment . Fits all 1974 and earlier Rochester Quadrajet carburetors, also some later year truck and marine carburetors. Dimension stamped in rod indicates maximum diameter of taper.
Quantity: 2 Primary Metering Rods for Rochester Quadrajet.
Cruise diameter: .039"
Power tip diameter:.026"
Rod overall length: 2.465" - 2.480"
Primary Rod Tech:
A 39 rod has a large diameter of .039" and a small diameter "power tip" of .026". The .039" section of the rod is positioned in the metering jet during light throttle driving. During heavy acceleration, manifold vacuum decreases allowing the power piston to rise positioning the small diameter (.026") power tip in the metering jet.
Larger diameter rods will lean part throttle/cruise air fuel mixtures. All " " primary metering rods have the same small diameter power tip (.026"). A great way to fine tune your Q-Jet for better driveablity and fuel mileage.