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Old 05-15-2012, 05:20 PM   #1
hcm1957
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rough idle,low vaccum

I have a rebuilt 350 270 hp engine. Original quadra jet rebuilt and runs rough. Have low vaccum. Help
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Old 05-15-2012, 07:45 PM   #2
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Re: rough idle,low vaccum

Wow pretty general. vacuum leaks obviously, valves too tight, timing wrong, for starters.
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Old 05-15-2012, 07:52 PM   #3
danielsatur
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Re: rough idle,low vaccum

Do a smoke test to pinpoint any vacuum leaks.
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Old 05-20-2012, 12:22 PM   #4
hcm1957
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Re: rough idle,low vaccum

Timing is on, Lifters are adjusted correctly and no vacuum leaks around intake.All vacuum lines are plugged. still have rough idle and can not adjust idle mixture screws
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Old 05-20-2012, 02:35 PM   #5
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Re: rough idle,low vaccum

Compression test next. Or short out one wire at a time see if one cylinder does not change the engine speed or roughness.
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Old 05-20-2012, 03:37 PM   #6
DeltaP
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Re: rough idle,low vaccum

My 2 cents: Faulty or incorrect PCV valve or hoses. Poor valve seating. Restricted idle passages. Bad coil. This is in addition to everything else mentioned.
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Old 05-20-2012, 06:00 PM   #7
hcm1957
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Re: rough idle,low vaccum

Thanks for your 2 cents. All new hoses and pcv, heads where redone and running hei.
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