L48 idle issues
Thread Starter
Intermediate
Joined: Dec 2009
Posts: 26
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L48 idle issues
The L48 in my 1977 vette is not idleing smooth. When I crank it in the morning it will idle up to about 1,000 to 1,100 RPM. Then if I turn it off and recrank it it will go to about 600 RPM where I set it to idle. I dont know if I need to rebuild the carburetor or what. If anyone has any advice I am open to ideas. Thanks
Racer
Joined: Nov 2009
Posts: 486
Likes: 1
The L48 in my 1977 vette is not idleing smooth. When I crank it in the morning it will idle up to about 1,000 to 1,100 RPM. Then if I turn it off and recrank it it will go to about 600 RPM where I set it to idle. I dont know if I need to rebuild the carburetor or what. If anyone has any advice I am open to ideas. Thanks
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
That is normal behavior for a mid-70's Detroit-built vehicle. These were pre-computer. Today the computer regulates fuel flow, etc. and can quickly drop idle speed back to 600 rpm and keep it running smooth. With a carbureted engine, that isn't so easy. Cold fuel doesn't atomize as well in a carb as does high-pressure fuel through fuel injectors in newer cars. So, there was a choke system with a fast-idle adjustment as well as a standard idle speed adjustment for when the choke dropped up (after engine warm-up). You need to adjust your carb as described in the Chevrolet Chassis Service Manual for your year car. There are detailed instructions and photos for all of the carb and choke settings and adjustments. And they really work! 
