Can someone please explain "fast idle" in English?

[79_Limited]

This past weekend I got the engine time which helped tremendously. It was timed at 20+ BTDC which explains why the engine was idling too high and dieseling when shut off.

I reset set it to 10 BTDC. The technical manual called for 8 but I set it to 10 since I am running HEI.

Anyway, I then set the curb idle on the carb (Motorcraft 2100) and set the RPM's to 600.

These two things were an immediate improvement but not quite perfect.

Can someone please explain to me what fast idle is and how I adjust it? I know when I start the Wag right up it does not rev right up to a fast idle but at just a normal idle. My electric choke is working.

[The Anti-Chrysler]

There is a separate idle speed adjustment on the opposite (pass.) side of the carb. for fast idle. The highest cam setting should match the RPM setting listed on the engine sticker on the core support.

[The Anti-Chrysler]

Oh, and fast idle is just the choke holding the throttle on a faster idle to help the engine warm up and keep it running when it's cold. Fuel injection systems do that automatically, with some it's not even necessary.

[brad_fsj10]

For two barrel Carter carburetors -

There are two screws near the throttle lever and cable mechanism. The outer screw is used to set the curb idle (600 as you stated).

The inner screw is to set the fast idle. The choke mechanism should move a cam mechanism under this second fast idle screw. This cam has teeth or "steps" on it that, when rotated forward (toward the front of the jeep), hold open the throttle plates. It accomplishes this by catching on the fast idle screw.

To set the fast idle speed, get the engine warmed-up to normal operating temperature. While ideling, open the throttle a little and rotate the fast idle cam forward. Allow the throttle to close so that the fast idle screw rests on the (usually noted) second cam step from fully rotated. The engine should now be ideling fast(er). Adjust this fast idle speed to 1200 rpm (stated on most emissions stickers).

Personally, I like it at about 900 but that's up to you. Hope this helps.