ID 2150 carburetor

[85lebaront2]

How can you set the cold fast idle speed when the engine is HOT?

I set mine by quickly adjusting the fast idle speed screw as soon as the engine was started cold. You have to hurry, because the idle speed will quickly increase as the engine begins to warm up.

I just went out and drove Lucille and this is my observation:

My cold fast idle is set at 1500 RPM. That is, it initially *starts* there, but then the engine will slowly climb up in RPM if the engine is allowed to run without disturbing it. In fact, it will usually climb up to 1750 RPM within 30 seconds or so, which is when I go ahead and gently blip the throttle to get the idle speed down to the next lower step of 1000 RPM. (This is usually when I drive away. As the engine warms up even more, the idle speed will return to the normal curb idle of 750 RPM.)

The 2000 RPM "hot" setting must be what Ford used to get an easier, more consistent adjustment without rushing through the process? i.e. if the "hot" setting is set to 2000 RPM, then perhaps the engine will start at 1750 RPM when the engine is cold?

Is that how it works?

With the engine warm, shut it off, disconnect anything the label says to (like EGR) open the throttle and raise the fast idle cam to the specified step then start it up, or you can reach the cam to raise it with the engine running. It is specified warm as cold would be too variable.

[LARIAT 85]

With the engine warm, shut it off, disconnect anything the label says to (like EGR) open the throttle and raise the fast idle cam to the specified step then start it up, or you can reach the cam to raise it with the engine running. It is specified warm as cold would be too variable.

Ah, I understand now.

That makes the adjustment a whole lot easier than my method of trying to adjust the fast idle speed screw before the engine begins to warm up.

Thanks, Chief!