3rd Gen / L98 Engine Tech 1982 - 1992 Engine Related

idle problem....

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Old Sep 14, 2003 | 07:23 PM
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idle problem....

yea, my new 350 isn't doing it....is a vacuum leak the only possible explanation?

It holds like 1500RPM strong, sounds great, throttle response is great, revs perfect, no hesitation...you try and adjust the carb/ignition to get it to rev below like 1500 though and it just dies....it's gotta be a vacuum leak right? We put a gauge on, 17PSI at 2500+, 11PSI at 1500, like 7 once we let it below 15.....blah....sounds mean as hell though
Old Sep 15, 2003 | 07:39 AM
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What does the can of brake cleaner say? Where are you getting this vacuum readings?
Old Sep 15, 2003 | 07:41 AM
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You sure you are getting +17 psi readings? If you are getting -17 it is fine but you shouldn't be getting +17 psi
Old Sep 15, 2003 | 11:24 AM
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I mean 17+PSI of vacuum, all those numbers are in vacuum.

The gauge is plugged into the carb where it would normally hook up into the distributor....it's a automotive gauge for vacuum....

we're going to reinstall the intake.....but if there anything else it could be?
Old Sep 15, 2003 | 11:50 AM
  #5  
cwalsh
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If I am not mistaken you want the vaccum to the distributer to pick up with RPM(ported) not fall off. that could be your problem.
Old Sep 15, 2003 | 02:25 PM
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#1 The distributor does not have the vacuum line attatched to the carb, I was told by the guy helping me that baseline ignition is done w/o vacuum to the carb.

#2 The vacuum line on the carb that normally goes to the distributor is not going to the distributor, thats going to the gauge.

#3. I get 17+PSI of VACUUM at 2500+RPM, at 1500RPM I get around 11 PSI of vacuum, as soon as we let the engine rev below 1500 the car beings to stumble, the vacuum drops to like 6PSI and it then stalls within 3-5 seconds.

It holds 1500 well, it sounds clean, we checked to make sure every spark plug wire was in the correct place, when you rev the engine it sounds good and has no hesitation, response is instant. So right now the engine "runs", but it won't idle. Anything other then vacuum that could cause this? The vacuum lines from the carb to the positive crankcase vents are good, as is the brake booster vacuum line. So we're thinking that our idle troubles must be vacuum related, and it could be the intake.
Old Sep 16, 2003 | 12:28 AM
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cwalsh
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what kind of carb?
Old Sep 16, 2003 | 08:28 AM
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a 750 wouldn't work, so we put on a brand new 670 holley street avenger with the same results
Old Sep 16, 2003 | 10:58 AM
  #9  
cwalsh
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do you have the idle mixture screws adjusted properly?
Old Sep 16, 2003 | 01:13 PM
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yea, it's not the carb, we're thinking it could be the distributor also
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