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.



-Tom

1950 Chevy 3100 w/ 1956 235