Posted by gmharris [71.105.35.249] on Monday, December 09, 2013 at 15:13:35 :
In Reply to: Re: vac distributor posted by TGP (IL) [68.164.9.40] on Monday, December 09, 2013 at 13:41:41 :
Pre-emission control engines with vacuum advance will draw their vacuum directly from the manifold or from the carburetor before the the throttle plate.
Ported vacuum, after the throttle plate, was an early emission control tactic to keep the vacuum advance at zero during idle.