How is it possible, with the Vcan plumbed to the spark-port, to initiate a ping at WOT, on a throttle-stomp? The spark-port should be zero at idle, increasing at Part-Throttle with rpm, and go to atmospheric, as the throttle moves past it. And this should be instantaneous, with that footstomp.
But if somehow the Vcan is plumbed to a Venturi-vacuum source, then, yes the port will switch from zero at idle, to full manifold vacuum as the throttle moves past it, and could, at WOT, end-up higher than manifold vacuum, cuz it's measuring from the venturi............
Venturi-vacuum was used in the pollution era to either power up or signal, certain devices. I wouldn't expect to see one on an aftermarket 4bbl, but I have seen them on Thermoquads. Jus saying, put a vacuum gauge on the source port.
