I said in the previous thread that I believe both can be made to work well, or work poorly. It's all about understanding how each affects the car. There is not one simple answer that will work in all cases. Compression, vacuum at idle, settings for vacuum canister and distributor, carb size, etc. will all play a role for how the car behaves.
Ported and manifold vacuum are the same once you crack the throttle and start to drive away. The ported source "gets" its vacuum "from" the manifold.
Yes, but since you opened the throttle the vacuum drops, then will give less advance.
I tried several times on ported but when being gentle on the throttle i can hear i ping, when going back to manifold vacuum there is no ping.
For the ported i need to turn back the initial advance to less, say to 10-12 degrees, and then it will not idle at all.
A person who uses MVA will generally need to reduce their static timing since vacuum advance at idle will increase timing. Conversely, someone using PVA will have a tendency to increase their static timing since there will be no vacuum advance at idle.
But let's think of a couple of scenarios:
(Case #1) Running MVA with an aggressive cam so the engine makes low vacuum at idle. In this case, the initial timing is set higher, and the MVA adds only a little bit of timing. When this person starts to accelerate, the timing does not drop off very much, and then centrifugal advance starts to take over.
(Case #2) Running MVA with a cam that makes a lot of vacuum at idle. In this case, the initial timing is set lower, and the MVA adds perhaps 20 degrees of timing. When this person starts to accelerate, the timing drops off by 20 degrees until the centrifugal advance can start to increase it back. I believe that this case the car will perform better with PVA (set correctly) so the timing doesn't fall on its face when accelerating. Of course, there is SO MUCH that is tunable. As mentioned earlier, when and how much timing the vacuum advance and centrifugal advance apply can be adjusted.
VERY ROUGHLY, and based on most common settings for centrifugal and vacuum advance, I would say that a cam that produces high vacuum at idle may run better when tuned with PVA. Conversely, a car with an aggressive cam may run better with MVA.
Let the flaming begin...