How to rebuild a Rochester Quadrajet 4MV carburetor
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====Aneroid or spool location==== | ====Aneroid or spool location==== | ||
| − | There were also additional Q-jet designs used mainly in 1975 | + | There were also additional Q-jet designs used mainly in 1975-'76, that used an auxiliary enrichment system in addition to (or in some cases instead of) the primary PP system. One has an accordion-shaped aneroid "bellows" that lifted/lowered a single metering rod in a jet; it used no vacuum or power piston to operate it. The aneroid bellows changed the air/fuel ratio in accordance with the barometric pressure. Another was identical to the aneroid except the aneroid was deleted and was replaced by a filler spool that did not respond to barometric pressure; instead it was adjusted to give the correct air/fuel ratio according to ambient conditions only. These systems was found to be lacking, so were discontinued. |
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|[[File:Aneroid.jpg|thumb|center|350px|Red arrow points to aneroid adjustment screw through hole in airhorn. Hole is plugged with a cup plug.]] | |[[File:Aneroid.jpg|thumb|center|350px|Red arrow points to aneroid adjustment screw through hole in airhorn. Hole is plugged with a cup plug.]] | ||
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[[File:ANEROID OR FILLER SPOOL DETAILS.jpg|thumb|left|600px|Early APT, ca. 1975]] <br style="clear:both"/> | [[File:ANEROID OR FILLER SPOOL DETAILS.jpg|thumb|left|600px|Early APT, ca. 1975]] <br style="clear:both"/> | ||
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| + | The other system uses a vacuum operated PP like the primary PP, but it differs by using only one metering rod and one fixed jet to feed both sides of the primaries. These were abandoned soon after they were released; it was found the primary PP system could be tailored to meet the requirements without the added complexity of the auxiliary system. | ||
| + | [[File:Qjet aux PP 75-76.jpg|thumb|400px|left|1975-'76 auxillary power piston equipped Q-jet. This one is from a Pontiac]]<br style="clear:both"/> | ||
===Secondary tuning=== | ===Secondary tuning=== | ||
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