carb problem - Team Camaro Tech
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post #1 of 9 (permalink) Old Oct 29th, 02, 11:02 AM Thread Starter
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Steve
 
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Here is an interesting one. My 327 with a Holley 4150 600cfm will not run from 1000 to 2000 rpm's. There is just a dead zone there. If I slowly advance the throttle, the rpm's will stop advancing at 1000, even as I advance the throttle, but then suddenly jump up to 2000 rpm. It does this even if I adjust the idle speed into this "zone" and let it stay there. When I go back down the same thing happens, the engine will suddenly drop from 2000 to 1000rpm but not run anywhere between. Is there some kind of transition circuit that operates between the idle jets and the main jets?

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post #2 of 9 (permalink) Old Oct 29th, 02, 11:07 AM
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There is an off idle transition circuit. Sounds to me like it might be gummed up. When was the carb last rebuilt?

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post #3 of 9 (permalink) Old Oct 29th, 02, 11:32 AM Thread Starter
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The carb was installed new about 9 months ago. Is the transition circuit metered in some manner? Sounds like I need to pull and soak it.

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post #4 of 9 (permalink) Old Oct 29th, 02, 11:48 AM
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I think he's refering to the accel pump ckt as it's what gets you going off the idle ckt. Read this thread it may help you... https://www.camaros.net/forum/Forum9/HTML/008656.html

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post #5 of 9 (permalink) Old Oct 30th, 02, 09:44 AM Thread Starter
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Thanks for the thread. What has me baffled is that the same thing happens as I decrease throttle. The engine will drop steadly as I decrease throttle to 2000rpm, then suddenly drop to 1000rpm and stay there until the plates close and the idle circuit takes over. The engine will not maintain any speed between. I don't think the accelerator pump shot would effect the rpm's as the throttle is decreased.

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post #6 of 9 (permalink) Old Oct 30th, 02, 12:59 PM
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Blown power valve from a backfire?
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post #7 of 9 (permalink) Old Oct 30th, 02, 05:19 PM
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<BLOCKQUOTE>quote:</font><HR>Originally posted by Chris Davis:
Blown power valve from a backfire?<HR></BLOCKQUOTE>


I just installed one of those power valve protection check balls. Fairly easy considering I was rebuilding the carb. I sure hope I can avoid the headache of blown power valves now. I've blown a few.

-dnult
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post #8 of 9 (permalink) Old Oct 30th, 02, 06:40 PM
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Just try unscrewing the idle mixture screws and give a long squirt of carb cleaner in each one. Also clean the idle air bleeds near the venturis.
Make sure to use a good fuel filter.
David

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[This message has been edited by davidpozzi (edited 10-30-2002).]
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post #9 of 9 (permalink) Old Nov 11th, 02, 04:36 AM Thread Starter
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I gave the carb a good cleaning and did as Davidpozzi suggested. All is well, runs great now. Thanks to all.

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