Quote:
Originally Posted by David Ray
WRONG.
Since ported vacuum is taken further up the throttle bore, well within the smallest diameter of the venturi, vacuum is created there, to pull a vacuum advance diaphragm into adding timing during acceleration, or, make a second acceleration timing curve..
The vacuum signal at the base of the carb at WOT is extremely low, to completely NIL, so, no vacuum pull, no vacuum advance timing on full manifold vacuum sourcing at full throttle, NO secondary acceleration timing curve..
VAST difference with vacuum levels between full manifold and WOT ported sourcing.
Try driving around with TWO vacuum gauges connected, one to each type port, as I have, many, many times.
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I can assure you i know the difference between the ported or the full manifold source for the ignition vacuum advance, and why either is used.
Wouldn´t it be easier for you to just give an example on any carb or engine that uses a ported source to add a second advance curve from the ignition vacuum advance, instead of twisting and turning my words against me and make up fantasy statements?
Thanks.