"ported Vaccum Signal" (1 Viewer)

Mar 18, 2005
I've been doing a restoration on my "72 40. I put a GM HEI diz with vac advance. Question is, according to MAN-A-FRE you need a "ported" vaccum signal with vac advance distrib. Some sort of valve that retards the diz until the throttle is applied. This all makes sense, but I never even heard of one, let alone seen one. Any thoughts on this would be appreciated.

The article is in the MAN-A-FRE tech sec under FAQ webber carb fuel milage
Mar 27, 2003
Georgia Tech
search for ported vacuum, there should be threads on where you drill the aisin carb for ported vacuum.

Ported vacuum is the opposite of the vacuum from the intake manifold (eg, when one is high, the other is low).

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