Holler at him and see. I suspect that he is referring to ping caused by sudden increased in throttle resulting in faster burn conditions in the chamber which requires the reduction in timing to compensate.
The argument regarding ported vs. manifold is never ending. I got no comment on that because of lack of experience. I am going for no vac adv first then migrating to manifold after I recurve / limit my mech and start tuning my vac can. But my guess is that the difference would depend on factors of timing curve, total, initial, and engine build / load.
Considering how much trial and error is involved in setting up all those variables, maybe talking to this guy and a few others with years of experience about base line timing setups based on builds would be a good way to get you 75% closer to perfect timing.
I am dealing with a very mild 440 in a 4200# car, so timing is going to be challenging. I gotta get timing tape and a piston stop and set my balancer marks first. Then drill a hole in my cap and see if my rotor is phased decently. Then the next forty steps to this archaic timing curve operation. :) ahhh the fun of working with old iron. May as well be a timing the valves on a steam engine compared to this new stuff running down the street.
So he says to use the manifold vacuum instead of ported vacuum (thats usually recommended). I think I understand why he says this but does anyone care to elaborate more on it? Oh and WTH is gas knock?