400 2v Idling Issues
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Posting Guru
Joined: Nov 2004
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From: Northeast Nebraska
400 2v Idling Issues
Ive got a 78 F-250 AT 4x4 with a comp 256xe cam and 400 stock 2v carb. When I fire it up cold it idles good but high rpm's (around 1500 rpm). When warm it surges and wont keep a steady idle then dies. When I put it in gear its even worse. It basically sounds like its gasping for breath. Ive tried 2 different carbs and the second is worse than the first. Should I be looking for vacuum leaks, rebuild the carb or is this an ignition issue?
Post Fiend
Joined: Dec 2006
Posts: 9,111
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From: Lexington Mo
Sounds like a vacume leak bud. If you can keep em' running you can try spraying carb cleaner around the intake manifold, carb base gaskets. EGR too, maybe around the vacume line from the intake manifold, to the power brake booster. If you try this, the engine will nearly die when it sucks in the carb cleaner.
Bob
Bob
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From: Northeast Nebraska
After messin with it some more last night its definitely got to be some sort of vacuum leak. It runs better with the choke slightly closed. Im gonna rebuild the carb tonight and put on a different egr spacer with all new gaskets then go from there. I might even switch out my dizzy cause the one thats in there doesnt seem tight where the cap meets the round plastic deal where the rotor sits. And who knows....maybe the vacuum advance is my culprit.
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Posting Guru
Joined: Nov 2004
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From: Northeast Nebraska
Did you do any special recurving of it or was it all plug-and-play? Ive been thinking of getting one since I can reuse it when I upgrade to a 460.
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Posting Guru
Joined: Nov 2004
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From: Northeast Nebraska
I think I got my idle issue fingered out. One of my vacuum hoses wasnt in the right spot so it threw everything else off.
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