At idle, cruise (light throttle) the same amount of vacuum is available under the throttle plates. It will activate the vacuum advance regardless if it is hooked up to a "manifold" or a "ported" source. If you are getting part throttle "ping" reduce the amount of travel in the vacuum advance unit or get an adjustable unit. This assumes that you are happy with the current initial and total timing settings being provided by the mechanica advance.....Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran!
https://cliffshighperformance.com/
73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
|