Join Date: Sep 2000
Location: Washington, Michigan USA
1-2 is right - you always measure intake manifold vacuum to determine power valve values, as that's what the power valve actually sees - manifold vacuum, not "ported" vacuum. Your total timing is set with the distributor vacuum advance line disconnected and plugged; total timing is initial plus centrifugal, period - vacuum advance comes and goes depending on engine load, and is totally inoperative at wide-open throttle anyway, so you don't include it for total timing.
'69 Z28 Fathom Green