Idle problem
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Joined: Oct 2002
Posts: 52
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From: wellington fl
Idle problem
I have a 1977 corvette with a 600 Elder Brock manual choke(which is not hooked up) and I have the idle sit at 900 rpm. Once the car warms up the idle will go from back and fourth from around 700 to 900. If I reset the idle to 900 rpm after the car warms up it still does the same thing. The last person to mess with the carb was Eismann's but they are closed today. I just clean the K&N air filter and I checked to make sure all the carb bolts were tight. Any suggestions.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
I have a 1977 corvette with a 600 Elder Brock manual choke(which is not hooked up) and I have the idle sit at 900 rpm. Once the car warms up the idle will go from back and fourth from around 700 to 900. If I reset the idle to 900 rpm after the car warms up it still does the same thing. The last person to mess with the carb was Eismann's but they are closed today. I just clean the K&N air filter and I checked to make sure all the carb bolts were tight. Any suggestions.
If I am understanding you correctly you have an Edelbrock carburetor with a manual choke and your idle speed is varying between 700 and 900 rpm after its warmed up. I suggest setting the idle speed in NEUTRAL to 750 rpm and see if it'll stay there.
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
I have a 1977 corvette with a 600 Elder Brock manual choke(which is not hooked up) and I have the idle sit at 900 rpm. Once the car warms up the idle will go from back and fourth from around 700 to 900. If I reset the idle to 900 rpm after the car warms up it still does the same thing. The last person to mess with the carb was Eismann's but they are closed today. I just clean the K&N air filter and I checked to make sure all the carb bolts were tight. Any suggestions.
Have you watched the choke to see if it's moving or fluctuating? The symptoms sound a little like a vacuum leak though.
Melting Slicks
Joined: Jan 2014
Posts: 2,478
Likes: 254
From: Downers Grove Illinois
I have a 1977 L-48 with an automatic transmission and mine does something similar. It started doing it just over a year ago and I still haven't figured it out. I changed, plugs, wires, distributor and fuel filter. I have looked for vacuum leaks and so far haven't found any. Mine will sit at 900 in park and then when it warms up drop and stay at a rough 700 RPM. If I rev it a few times it will settle back at 900 and then shortly drop to 700 and stay there unless I rev it up again. It is pretty noticeable driving around when I stop at a light.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
What intake? I caught a problem on my 66' with 650AVS and Performer intake....it sucked air in the front....always erractic around idle and taking off.....
I put Edelbrocks card plate on it as there was a tiny slit of open carb throat exposed along the front...almost imperceptible....you would think an Edelbrock carb on their intake would not need it...but ????????
Take some Carb Spray or Propane torch (not lit-just gas) and spray or wave the gas around the carb base to see if idle changes. If so...you found it. Do it where the runner meets the head too.
Jebby
I put Edelbrocks card plate on it as there was a tiny slit of open carb throat exposed along the front...almost imperceptible....you would think an Edelbrock carb on their intake would not need it...but ????????
Take some Carb Spray or Propane torch (not lit-just gas) and spray or wave the gas around the carb base to see if idle changes. If so...you found it. Do it where the runner meets the head too.
Jebby
Last edited by Jebbysan; Nov 13, 2015 at 03:02 PM.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
I assume you are using a square bore manifold with your square bore carburetor? If not and you are using one of those 1" thick adapters make sure the gaskets on the top and bottom of it are clearly showing it is sealing with no signs of any places where leakage could be occurring.
Last edited by toobroketoretire; Nov 13, 2015 at 03:10 PM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
The Performer has the bolt pattern for both styles but the throat is a Spread Bore style....the 600 Edelbrock bolts right on...but not enough coverage on the front leading edge.
You will need this if this is what you are running:
http://www.summitracing.com/parts/edl-2732
I post this for other to see really....as it is not well known.
Jebby
You will need this if this is what you are running:
http://www.summitracing.com/parts/edl-2732
I post this for other to see really....as it is not well known.
Jebby
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