IMO, I think the only way ported would work better would be if the timing curve ( and vacuum advance cannister ) was set up specifically for it and the result would be sleightly more throttle response. If you had your distributor curved properly and with the right vacuum advance cannister, then I say manifold vacuum wins because of the better idle and milage. I say better milage because I would assume the throttle is light enough during cruising where ported vacuum may not have even kicked in yet. Again though, maybe some carbs are calibrated differently so...
Overall I would say that this topic has caused many debates ( and arguments! ) over the years so in the end you just have to test it for yourself. I personally never noticed any advantage when running ported vacuum but have noticed the obvious disadvantage of having much poorer idle quality and the engine runs a tad hotter too. Running manifold vacuum fixes that and my throttle response stays the same so it was an obvious choice for me.
Overall I would say that this topic has caused many debates ( and arguments! ) over the years so in the end you just have to test it for yourself. I personally never noticed any advantage when running ported vacuum but have noticed the obvious disadvantage of having much poorer idle quality and the engine runs a tad hotter too. Running manifold vacuum fixes that and my throttle response stays the same so it was an obvious choice for me.
