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10-10-2011, 01:06 AM
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#1 |
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Registered User
Join Date: Oct 2011
Location: phoenix, az
Posts: 508
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Vacuum Leak?
My mid 70's BB idles rough and low so I'm thinking the cause is a vacuum leak I can only hear while accelerating, not hard just normal acceleration. I've sprayed WD-40 around the carb and intake gasket surfaces and bolts but no change in idle so I'm wondering what it could be?
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10-10-2011, 01:47 AM
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#2 |
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Registered User
Join Date: May 2009
Location: San Antonio,Texas
Posts: 220
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Re: Vacuum Leak?
A vacuum leak would make it high idle. Not low idle. Sounds like another problem to me. maybe a dirty carb, it may need a good internal cleaning or a rebuild.
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10-10-2011, 03:45 AM
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#3 |
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Registered User
Join Date: Oct 2011
Location: phoenix, az
Posts: 508
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Re: Vacuum Leak?
The sound I hear sounds like vacuum leaks I've had before that why I thought it was but if not then what can be making that sound?
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10-10-2011, 11:53 AM
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#4 |
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Registered User
Join Date: Dec 2010
Location: Pittsburgh, PA
Posts: 1,009
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Re: Vacuum Leak?
Check all the hoses to see if you find one dryrotted/disconnected. Especially the vacuum advance. The low idle could be a carb adjustment. If you only notice the rough running when accelerating, make sure to check the vacuum advance and the weights inside the distributor. Sometimes if an engine has sat for a while, the weights will rust or seize together, making the vacuum advance not work correctly and it will give you problems under acceleration.
__________________
Steve Member of the Foot Pedal Club '83 Chevy K20: 6" Rough Country, 3" Performance Accessories BL, Bushwacker Cutouts, 38x15.50 Mickey Thompson Baja Claws, 350 HP 350 crate engine from Jegs, Turbo 400 
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10-10-2011, 06:12 PM
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#5 |
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Registered User
Join Date: May 2009
Location: Pinehurst, Idaho
Posts: 311
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Re: Vacuum Leak?
check plugs for lean condition if you haven't already
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10-10-2011, 08:51 PM
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#6 |
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Registered User
Join Date: Aug 2011
Location: Bradley, South Carolina
Posts: 277
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Re: Vacuum Leak?
dry ice, water.. remove the fan belt, start the engine.. the ice 'smoke' will locate a vacuum leak in 30 seconds.. do not run it with out the belt any longer then it takes for the thermostat to open.. i've used this twice and both times it was worked.
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10-10-2011, 08:56 PM
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#7 |
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Registered User
Join Date: Jun 2011
Location: Richmond,Va
Posts: 2,934
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Re: Vacuum Leak?
Find a shop with a smoke machine. I use one every day to find vacuum leaks. Pay to have it tested and take it home to fix it.
__________________
Nick Carter 1967 C10 Short bed Fleetside Project Cheap Thrills! 2WD C10 Modern/Performance Alignments Easiest Alignment Ever! |
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