While cranking were talking the (+) side of the coil should have close to battery voltage or the (-) side?
While cranking the + side of the coil should have battery voltage.
When measured with a voltmeter (a slow acting measuring device), the - side of the coil will be varying between zero volts when the points are closed, to battery voltage when the points are open.
If measured with an oscilloscope or your finger, the - side of the coil is much more interesting. When the points close, current flows through the primary winding of the coil creating a magnetic field that is transferred to the secondary winding of the coil. When the points open, current flow in the primary winding stops, the magnetic field collapses and the secondary winding produces the high voltage pulse that eventually is transferred to a spark plug. That same collapsing of the magnetic field causes a pulse that can be measured at the - side of the coil, sometimes measuring 200+ volts for a very short period. Picture below is worth a thousand words. Blue oscilloscope trace is voltage at the coil - terminal. Red is current measured at the same place.
