High Idle
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Senior User
Joined: Dec 2003
Posts: 154
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From: Somewhere, HI
High Idle
Okay, the site has to much traffic right now for me to do a search. So in case this has been discussed I am sorry. I don't have my shop manual yet and I was hoping one of you could help me out.
I have a 1970 F-250 with a 390. When it is done warming up I can kick it down to a lower idle but it does not seem to stay there. After driving for a little while it is still idling higher than it should. Not as high as the initial first-in-the-morning-idle, but still higher. I can kick it back down almost to a barely running idle, which may be lower than it should but I am not worried about that yet. Everytime I leave an intersection, by the time I get to the next one, it is idling higher again! Any suggestions?
I have a 1970 F-250 with a 390. When it is done warming up I can kick it down to a lower idle but it does not seem to stay there. After driving for a little while it is still idling higher than it should. Not as high as the initial first-in-the-morning-idle, but still higher. I can kick it back down almost to a barely running idle, which may be lower than it should but I am not worried about that yet. Everytime I leave an intersection, by the time I get to the next one, it is idling higher again! Any suggestions?
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
I'm assuming the orginal Autolite carb and choke?
Sounds like it needs adjusted down a notch. Like it gets cooled a bit driving and starts to close. In turn, bringing idle up. Loosen the three screws and turn it.
Once you get the high idle set so that it does not raise rpm, adjust your main idle screw for proper speed.
Larry
Sounds like it needs adjusted down a notch. Like it gets cooled a bit driving and starts to close. In turn, bringing idle up. Loosen the three screws and turn it.
Once you get the high idle set so that it does not raise rpm, adjust your main idle screw for proper speed.
Larry
Elder User
Joined: Aug 2003
Posts: 952
Likes: 1
From: iowa
does your choke have the choke plate on it ???
the blowing air from your fan will blow on the choke and cause it to cool down which in turn puts the idle back up. i had this problem too until i put the choke plate back on the carb, now the air doesnt get directly too it so it idles down faster.
the blowing air from your fan will blow on the choke and cause it to cool down which in turn puts the idle back up. i had this problem too until i put the choke plate back on the carb, now the air doesnt get directly too it so it idles down faster.
