if my memory serves me, manifold vacuum is essentially full time straight from the engine;
ported vacuum is regulated via the carburetor.
Brakes use manifold vacuum, because this permits the reservoir to gain signal at any time.
Ported vacuum is essentially delayed and regulated by the carburetor.
typically the manifold vacuum is taken directly off the intake, or on a feed line at the throttle body on the carburetor;
typically a ported vacuum signal is taken off of the fuel bowl on the carburetor.
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1970 Formula 400 Carousel Red on black (std) interior "no drivetrain option" car (same base drivetrain as GTO) 1:411 1970 Firebird Formulas originally sold in Canada
This should look just like your carb. The bottom right corner, in the picture of the carb, I put a black oval around the ported vacuum nipple where the distributor vacuum should be hooked up.
