That would be Don, and yes it is his way or the highway, that's for sure.
Hmmmm, then I guess the "engineers" at Edelbrock are crazy also. I did not email him, rather a long in depth conversation about it. I was of the mind that it must be Ported also. After listening to his reasoning, not ramblings, it made total sense. And apparently Edelbrock, Holley engineers tend to agree.
All I'll say is when it was time to buy a new carb for my Charger he could have one built to my specs for less than I could buy it from Summit for. He was very thorough with gathering the needed information and when the QF showed up at my house I've never been more impressed. I couldn't get it closer than it was.
Distributors are distributors, chevy, ford or Mopar. Mopar used "Lean Burn" chevy/ford some other form of electronic spark/timing control. "All" of those took vacuum from ported. Pre electronic carbs/spark control, took manifold vacuum.
Not exactly. My original 4429S in my 68 has one source for distributor advance and that's ported. Nothing else.
Manifold vacuum allows you to run a little less initial mechanical timing and ramp up initial timing via vacuum for a better idle n heat control with a modified engine n crap gas. The key to it is adjusting the vacuum canister. Not all engine combos are the same so can't tell you where yours should be. As you come off idle and accelerate normally, vacuum will rise, ported or Manifold and the distributor will act the same either way. At higher rpms, highway cruising, you want a lot of timing. Vacuum will be very high and the same using either, thus pulling more vacuum advance and using mechanical/centrifugal advance. As soon as you stab the accelerator to pass, Manifold vacuum will drop instantly, reducing timing back down to max mechanical/centrifugal advance that engine makes without detonation. W ported, the venturi effect of the throttle ventures will momentarily increase vacuum at that full throttle burst. For a moment, you will advance timing a little more before vacuum falls back down. The cars that came with old fashioned electronic emissions controls would use a sensor and reduce the timing electronically during that hard initial full throttle. Manifold vacuum on a car with "no" electronic emissions control will never be wrong. Ported vacuum on a car w no electronic emissions control, depending on modifications, weather, driving conditions etc... "may" cause a detonation issue when going to a full throttle "stomp", not always.
I've been doing this a long time and I have never seen a Chrysler product that used direct manifold vacuum advance. Always ported.
When you stomp on the accelerator the accelerator pump dumps significant fuel into the engine. So it goes from a lean to a rich setting. Lean mixtures burn slow (need more timing), rich mixtures burn fast (need less timing).
