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#1
11-30-2012, 02:49 PM
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Choke pulloff ?
1980 something Q jet with elecric choke and vacuum operated adjustable choke pulloff. How much should the choke pulloff open the air flap immediately afer starting the cold engine?
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#2
11-30-2012, 02:52 PM
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The adjustment varies by application but 1/4" is going to be close.
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#3
11-30-2012, 04:34 PM
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I have found .170" -.180" at upper chokeblade edge works fine.
Also, set fast idle speed, with hot engine/choke off, on fast idle cam high step at 1800-2000rpm. |
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#4
12-01-2012, 09:12 AM
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Remove the air cleaner and plug any vacuum lines going to it.
Get the phillips screwdriver ready at hand and pump the throttle twice and do a cold start. You have to move pretty quickly before the intake heats up and choke starts to "unload". Adjust the pull-off to "unload" the choke flap so the engine stays running smoothly, not bellowing from being too rich, or stalling out from being too lean. There is no magic setting for this, as just about every carburetor is different, and the engine under it as well. The distributor plays a role here as well. If it's set up with a lot of spark advance at low rpms, it's going to require a leaner choke setting. Some carbs don't have several "steps" on the fast idle cam to keep lowing high idle rpm's as the choke opens, so you also have to set the fast idle cam/rpms to suit your needs, in conjuntion with how far the pull-off unloads the choke flap on the first cold start........Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#5
12-01-2012, 06:39 PM
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Thanks guys. The airflap was staying WAY too far closed before. I'm getting closer. I need to let it cool down and try it again.
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