I know our engines get no vacuum advance at idle, but not too many years later, Chevrolet went to full vacuum advance at idle and as manifold pressure drops through throttle opening and increased load, less vacuum advance until zero at full throttle, then back the opposite way in the emission years to ported vacuum. It has gone every direction, run what works best on your application, a nice bit of vacuum advance for cruising makes for fuel efficiency.
Last edited by sstock; 05/12/2019 7:48 PM.
1953 Chevrolet 3100261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY GalleryVideo of the 261 running1964 GMC 1000305 Big Block V6, sm420, the next cab off restoration
