A paper by Lars Grimsrud
OverviewThe Rochester QuadraJet uses an automatic choke system that is actually very good, if properly set up and adjusted. But before starting on the choke setup, it’s important to remember a few other tuning parameters. The Q-Jet choke setup assumes that other engine parameters are correctly set up and tuned. Most importantly is proper ignition timing. Before doing any carb tuning, it is imperative that the initial timing, total timing, timing curve, and vacuum advance systems be correctly set up and functioning. You cannot correct tuning issues related to timing by tweaking the carb. See my papers on setting up timing and vacuum advance before you start playing with carb adjustments. Also, the choke setup assumes that your carb is correctly jetted and set up. If your carb is running either rich or lean, the choke will not function properly, even when adjusted to specification. Make sure your carb has the correct jets, rods and float level adjustment before trying to set up the choke. These carbs are old, and most of them have seen some “creative” jetting over the years. See my paper on Q-Jet setup for a listing of carb numbers and correct jetting.
This tech paper will discuss basic set-up of the Q-Jet automatic choke systems.
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