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Hal, Chevy Master Tech
Category: Chevy
Satisfied Customers: 1031
Experience:  ASE and Chevy Master , 31yr Dealership exp,
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Idle speed..the carb to a rebuilt one and it starts fine, but it idles

Resolved Question:

Idle speed adjustment L-69 . I have changed the carb to a rebuilt one and it starts fine, but it idles at 2000 rpm. I checked all the vacuum lines and it still idles high then jumps to 4000 until I shut it off, then it starts back at 2000 rpm. Any suggestions?
Submitted: 5 years ago.
Category: Chevy
Expert:  Hal replied 5 years ago.

Hi Paul, my name is Hal


Have you checked to make sure the fast Idle cam is off and the choke is fully open?

Customer: replied 5 years ago.
Yes the choke is fully open and I disconnected the fast idle cam because after it runs for a while the fast idle cam engages and pushes the throttle linkage, thats when it hits 4000 rpm.
Expert:  Hal replied 5 years ago.
Are the primary butterfly closed ?
Customer: replied 5 years ago.
I not exactly sure what your refering to, I am not a mechanic,but if its the front flap on the carburator it is open and the rear are closed
Expert:  Hal replied 5 years ago.

That is what i'm referring to. The front butter flys are the small discs attached to the shaft.

There is a screw on the drivers side of the carb that is for the base idle adjustment.

Turn it out so the shaft will close the primary butterflys. This will lower the idle.

Look at the picture below . do you have a idle control motor that looks like #82 in the picture. If so , we may need to make sure it is operating and if it is , we will need to adjust it.

Note this is the factory carb, is this the style you installed?



Customer: replied 5 years ago.
I will try that adjustment, also I am not sure where the idle speed motor is located, the blow up shows it off the carburetor, is on the driver side or passenger side, high or low
Expert:  Hal replied 5 years ago.

It is located on the drivers side and it is pretty large , you would not miss it. It touches the throttle lever where the cable attach's.

Base idle should be about 600 rpm in gear( D) If it has the idle control motor Base idle will be 475-500 with the motor shaft not touching the throttle lever.

I will walk you through the adjustment if you need help.

Thanks Hal

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