inline 6 that surges at idle

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Jul 2, 2008 | 10:49 PM

F-100/F-150

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inline 6 that surges at idle

I have recently put a new clifford intake and exhaust on my 300 with a new holley 390 on it. I had exhaust and intake leaks but seemed to fix them with remflex gasket. Now that I have done that the truck surges/ runs rough at idle. I have sprayed the intake and exhaust with some brake kleen to see if I have a leak and seem to have found none. The book says the main cause of this is vacuum leak. Any tips and suggestions?? Thanks

Compression is fine (I rebuilt the motor a little over 6K ago.)
cap and rotor are in excelent shape.
new fuel filter with the new carb

Jul 3, 2008 | 06:21 AM

srercrcr

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I would think the carb isn't set up right.

Jul 3, 2008 | 08:14 AM

fmc400

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Joined: Apr 2004

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From: Austin, TX

I know this probably isn't what you came here to be told, but that really does sound like a vacuum leak. Check that the intake was torqued in the proper specification and sequence. Check that the carburetor is bolted down evenly and snug. Also, make sure you didn't leave any vacuum connections open. Carburetors and intakes are full of fittings and openings for you to connect vacuum lines to and it's easy to forget to plug one of them.

Jul 5, 2008 | 10:25 AM

F-100/F-150

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Thanks,

It turned out to be the pcv valve system. If the PCV valve and charcoal cannister are hooked up to the carb it runs fine when the engine is cold. But once the engine gets warmed up thats when the surging starts. With that system disconnected and that port on the carb plugged it runs really nice and smooth. Does anyone have any pictures of how there is set up. Thanks.