Fluctuation in Idle speed

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ThinLizzy13
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Joined: October 5, 2012, 5:29 am
Location: Catskills NY
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Fluctuation in Idle speed

Post by ThinLizzy13 »

My '63 uni with a 223 and Autolite 1101 with a manual choke has an odd fluctuation in idle speeds. The best way I can describe it is it is acting like an automatic choke.
The truck will idle fine at 500-550 rpm. If I hit the gas quick it idles up like a choke was set to around 1000-1200 rpm. Sometimes I can get it to idle back down by pumping the gas, but most of the time it either stays idling high or will idle back down randomly.
I sprayed for vacuum leaks around the carb and did not find any. Timing is good; ignition is set to spec; truck otherwise runs perfect.
Am I missing something obvious here? :hm:
'63 F100 223 3OT
‘20 F150 XL
slick4x4
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Re: Fluctuation in Idle speed

Post by slick4x4 »

By the way you are describing...
If I'm understanding correctly...
It almost seems like you have some linkage hanging up...
I know the pedal hinge on mine was tight...
Had to take it out to lube it up...
Was it always like this... Or just get a little worse over time ?
If so... I'd say some linkage lubrication would help
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ThinLizzy13
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Joined: October 5, 2012, 5:29 am
Location: Catskills NY
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Re: Fluctuation in Idle speed

Post by ThinLizzy13 »

Thanks slick4x4, I think you're right. I found if I tap the pedal just right I can get it to idle down. I'll lube up the linkage tomorrow and see if that frees it up.
'63 F100 223 3OT
‘20 F150 XL
Leeroy
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Location: Melbourne, Australia
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Re: Fluctuation in Idle speed

Post by Leeroy »

Check the return spring on the carb also. Had this exact problem recently.
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