The numbers on the vacuum advance unit that are not the part number but are the specs for the vacuum advance. A typical set would be "5-12-8". The first
indicates inches of mercury at which the vacuum advance commences, the second number is inches of mercury at which the advance ends, and the third number is total degrees of advance provided by that unit.
A Mity-Vac is a good way to check if your new
vacuum unit is right on if you got "12" for inches of mercury at which the advancing action stopped.
Doug Reid HML
