Manifold Vacuum Experiment

I didn't read through every post but your findings don't surprise me RRR. When I was young (the 80's) and working on a lot of low compression, no quench, bad chamber engines I found most of them ran better when the vac adv was hooked to manifold vacuum. When I was tuning my 408 (10 to 1, good chamber design and .040 quench) it didn't like full manifold vacuum. My belief is the inefficient designs burn the charge slow so they need all the help they can get