[GMC Jim]

I would hope that this link could be made part of the FAQ's on engine timing.... Reading this excellent description on ignition timing will greatly enchance ones knowlege of the subject. In many cases, the detailed description of vacuum assist will be quite enlightening......... Jim (a believer that all HEI units should be checked on a distributor machine to determine the proper weights/springs combination for the RPM curve....in particular, for the adjustment and calibration of the higher RPM ranges..)