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Old 09-11-2003, 11:05 AM's Avatar is offline Moderator
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I admit, I don't work an anything with TPI or more than a PCV pollution control so my comment is couched it that old tech. I don't remember seeing the ported vacuum port showing up on carbs until recent years. It just makes more sense to my feeble mind to be sending the distributor advancing info based on manifold vacuum (engine load info, regardless of speed) rather than speed based info from the venturi port. The distributor already has speed info from the centrifugal advance. That is for old tech engines made B4 1970. Since then I know the engineers have come up with stuff I don't understand, thus the ported vacuum carbs.