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Old 06-02-2008, 09:07 PM
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Why vacuum on a timed vac port at idle?

Can anyone let me know what would cause a timed vac advance port to have vacuum at idle rpm (850)? This is on a holley 600 4160. Thanks!

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Old 06-02-2008, 09:12 PM
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Quote:
Originally Posted by Cousin_Joe
Can anyone let me know what would cause a timed vac advance port to have vacuum at idle rpm (850)? This is on a holley 600 4160. Thanks!
Throttle plates open too far....leaking base gasket.....cracked carb base.
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Old 06-03-2008, 08:28 AM
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Had an experience with the exact carb on a friends engine with a lumpy cam. I did all the things one would normally do for a 'tune'. Found the timed port still pulling almost as much as straight manifold vacuum. I tipped open the secondary plates a little, then closed the primary plates. Did the trick for this one. Went back through the idle A/F mix with a vacuum gauge and picked up more response and way better drive-ability.
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Old 06-04-2008, 07:05 PM
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I think the cause was the throttle plates too open, good call you guys. I cracked the secondary plates, turned down the primary plats, and no more vacuum on the timed vac port!
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