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Low idle


Guest paulmac1968

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Guest paulmac1968

When sitting idle and hot my idle is dropping to less than 500. When in gear the car has trouble not stalling because the idle drops so low. If I keep it running it runs smoothly. Is this just an idle adjustment issue? What's the proper way to adjust it?

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68 Bird?  Does it idle smoothly?  If so, just adjust the idle a little higher  using the adle adjustment screw.  If it's idling rough, it may be the idle mixture screws. 

 

Do you know what the factory recommendation is?  You might want to look it up.

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There might be a double-diaphragm vacuum advance on the distributor that's letting the ignition timing retard too much when at idle, or is not functioning.  Ford used some of those, but you might verify that your vehicle has one of those. 

 

Before I adjusted the idle speed, I'd make sure the engine's base timing is correct FIRST, adjust as necessary, then raise the idle a little IF it was still idling too slowly.  Might just need another 50-75rpm, so long as the raise didn't make the idle speed in "N" too high that the engine "diesels" when you turn the ignition "Off".

 

DON'T forget to check/replace the air filter element, if it might be causing the slower idle due to "clogging" from time/age/use.  Plus check the PCV valve as it's sort of a "calibrated vacuum leak" that has the specific purpose of drawing crankcase fumes from there into the base of the engine's carburetor to "recycle" and burn them.  Less flow, due to deposits inside of the valve, can mean less air entering the motor, just as an idle speed screw adjusted for a lower idle speed.

 

Please advise of your progress.

 

NTX5467

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