Multiple Spark Discharge. It's a CD box that delivers multiple sparks at lower RPM. http://www.msdignition.com/ --Bryan On Jul 30, 2014, at 2:34 PM, Tom Berg <thesuperscribe at yahoo.com> wrote: > I've got a Crane on my '64 Monza and it's worked very well. But, what's MSD? > > --Tom in Ohio >