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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1986GMCSierra on December 28, 2014, 10:58:22 am

Title: 305 FAST IDLE
Post by: 1986GMCSierra on December 28, 2014, 10:58:22 am

i have a 1986 stock 305 and 700r4 tranny.. what carburetor  would be best to stop a high idle and get a little more power out of the motor?

Title: Re: 305 FAST IDLE
Post by: Irish_Alley on December 28, 2014, 12:17:15 pm

High idle is a sign of a vacuum leak

Title: Re: 305 FAST IDLE
Post by: 1986GMCSierra on December 28, 2014, 01:23:22 pm

i guess it could be coming from my intake manifold both where it mounts to block and where carb mounts to it..

Title: Re: 305 FAST IDLE
Post by: 1986GMCSierra on December 28, 2014, 01:24:29 pm

Quote from: Irish_Alley on December 28, 2014, 12:17:15 pm

High idle is a sign of a vacuum leak

what is the easiest way to check for a leak?

Title: Re: 305 FAST IDLE
Post by: Irish_Alley on December 28, 2014, 01:33:37 pm

No easy way. Could be a vacuum hose leak, could be the carb or carb or intake gasket. Try and listen for a sucking sound. If you have some sort of starting fluid you can spray that around the carb and intake or something flammable like a propane torch not lit but turned on a engine vacuum leak could suck it up and will raise the idle