Manifold Vacuum Experiment

So we took Gladys into town today and I took some measurements on both manifold and ported vacuum. On manifold vacuum, at hot idle Kitty recorded 9hg. That's a big improvement over the 6-7 we had on ported vacuum. At 2200 at a steady cruise, we had 15hg. That's an improvement of 1hg before on ported vacuum. Small, but an improvement nonetheless.

On ported vacuum idling hot was zero, of course. At 2200 at a steady cruise, we had only 11hg. So that's 4hg less than manifold vacuum at a steady cruise. So clearly manifold vacuum is pulling in more timing at cruise than on ported vacuum. I must admit, I am surprised, as I figured they would be the same at cruise RPM, but they're not. This proves the theory that manifold vacuum pulls in more timing at cruise, at least in my instance.