How do I adjust the high idle adjustment on the carburateur for an older car?

What kind of car?--Carb?

The typical adjustment for carbs is the same, just different ways of doing the same thing.

1. With engine cold, press accelerator pedal to floor and release to set choke plate closed. There is a cam that moves in conjunction with linkage to set the throttle plates in a fast idle position.
2. There is a screw that rides on this cam, this is fast idle adjustment. Some can be adjusted with a screwdriver in this position, some need to be held at WOT to adjust the screw, obviously with the engine off. Locate this screw for future reference.
3. Start engine, if it doesn't fast idle, say around 1200-1600 rpm, then adjust screw to obtain rpm. If adjustment is of WOT type, wait for engine to obtain operating temperature.
4. When engine acquires some heat, not necessarily operating temperature, touch gas pedal, rpm should drop to curb idle.
5. Once engine has acquired operating temperature, turn engine off. If the WOT type of adjustment, open throttle to WOT position, locate screw and turn to adjust fast idle.

That's it in a nutshell, unless you're having problems withit running and giving it throttle when lukewarm, then you should richen/lean out the choke setting.



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Everett 68/350/PG/11.90/115mph

V-8, welcome to the site. Can you help us help you? We need to what kind of carb you are working on? Holley, Rochester Quadra Jet, Edelbrock? Then you can get a very accurate description of what to do.