Harvester,
I'm having trouble understanding why a vacuum gauge is best used along with a tachometer. Is the tach just used to set the initial RPM before using the vacuum gauge.
You say to advance the timing until EITHER the RPM or vacuum reaches a peak, then retard about 1"Hg drop in vacuum.
If it is EITHER and the vacuum gauge reaches the peak then why a tach too?
Also, I would prefer to use a timing light but I'm not sure if the flywheel/BB and or bell housing are correct for my engine.
