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Cold Start - Fast Idle Question

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Old May 5, 2017 | 07:01 PM
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LARIAT 85's Avatar
LARIAT 85
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Cargo Master
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From: Florence, SC
Cold Start - Fast Idle Question

Carburetor: Autolite 4100
Fast Idle Speed: 1250 RPM
Curb Idle Speed: 600 RPM (At normal operating temperature)

When I cold start my truck, the fast idle speed holds the throttle at 1500 RPM. I will let it idle about 30 seconds or so, and then I will tap the gas to bring the idle down.

When I do this, the idle will immediately drop all the way down, and too low for a cold engine. The engine won't stall, but it will hover just below 500 RPM, which is a bit too low to idle smoothly.

But when the engine is at operating temperature, the idle speed is 600 RPM and the engine will happily idle smoothly.

Shouldn't there be an "in between" speed? When I tap the gas pedal at 1500 RPM to bring the idle down some, shouldn't the speed drop down a little lower, like 1000 RPM since the engine is still a bit cold?

If so, what do I need to adjust?

The Autolite 4100 works PERFECTLY otherwise.
 
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Old May 7, 2017 | 04:17 PM
  #2  
LARIAT 85's Avatar
LARIAT 85
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Cargo Master
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Joined: Dec 2004
Posts: 3,362
Likes: 21
From: Florence, SC
Nevermind. I adjusted the choke cap a little bit richer and all is well.
 
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