Quadrajet
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In 1971 Pontiac had designed a special Q-jet that had the most flow of any production Q-jet, but because the modification decreased the vacuum signal on the primary side too much it was discontinued, so it was a "one year wonder" that fetches outrageous prices from restorers today. Many more 800 cfm Q-jets were installed from 1976-up. One way to locate a large casting carb is to source one from an '80-up light truck. Even the Chevy/GMC 4.3L V6 trucks used the large casting 800 cfm Q-jet! | In 1971 Pontiac had designed a special Q-jet that had the most flow of any production Q-jet, but because the modification decreased the vacuum signal on the primary side too much it was discontinued, so it was a "one year wonder" that fetches outrageous prices from restorers today. Many more 800 cfm Q-jets were installed from 1976-up. One way to locate a large casting carb is to source one from an '80-up light truck. Even the Chevy/GMC 4.3L V6 trucks used the large casting 800 cfm Q-jet! | ||
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==Power enrichment== | ==Power enrichment== | ||
| + | [[File:ANEROID OR FILLER SPOOL DETAILS.jpg|thumb|400px|Early APT, ca. 1975]] | ||
Most Quadrajets use a vacuum operated "power piston" (or "PP") to move the primary metering rods to control the air/fuel ratio, allowing the mixture to be leaner under low load/high vacuum conditions and richer during high load/low vacuum conditions. A less-common, early version uses a linkage attached to the primary throttle shaft to mechanically move the power piston. | Most Quadrajets use a vacuum operated "power piston" (or "PP") to move the primary metering rods to control the air/fuel ratio, allowing the mixture to be leaner under low load/high vacuum conditions and richer during high load/low vacuum conditions. A less-common, early version uses a linkage attached to the primary throttle shaft to mechanically move the power piston. | ||
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