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Old 04-06-2012, 02:51 PM
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Join Date: Mar 2001
Location: Cinnaminson, NJ
Cobra Make, Engine: Cobra Fibercraft Bodies 427 S/C, 351W disguised as a 427.
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Default Vacuum Advance - ported or manifold

I run a 1969 351W in my roadster. The distributor has a vacuum advance pot on it that advances the timing as higher vacuum is applied. OK, where should the vacuum advance hose be plugged in, a PORTED nipple or direct MANIFOLD nipple? There seems to be so much controversy surrounding this question. From what I read, direct manifold vacuum gives me 22 degrees of vacuum advance plus 10 degrees initial timing at idle for a cooler idle with less NOx emissions but ported vacuum gives me only 10 degrees initial timing at idle, slower idle speed but causes not only vacuum advance but also centrifugal advance to increase as engine speed increases.

There must be some expert out there who really knows his defecation (s**t) who can set me straight.
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