After getting my 53 GMC back from being worked on, I noticed it idles very fast, between 600 and 800 rpms. I read the procedure on how to set the idle using the throttle set screw and idle mixture screw. It appears pretty straight forward. So I attached my vacuum gauge and tachometer and started.

However, for some reason, the throttle adjustment screw doesn't appear to effect the idle. I can turn it 8 to 10 turns in both directions and the idle never changes. I can push down on the throttle lever and make the idle go down but as soon as I release the lever it starts reving up again.


What am I doing wrong or what do I need to do?

The carburator is a zenith 228. Also, I know the throttle pull wire is not interfering.

Thanks for your help,
Dale

Last edited by di1953gmc; 12/18/2011 9:01 PM.
When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.
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