my cars been down for 6 months WON"T SPARK

You didn't answer what type of ignition you have.

As for having 12v, you should have 12.6 with no load (each cell is 2.1 volts). Voltage WILL drop with a load and the starter is the biggest load the battery will see. You need to measure the voltage at the battery AND on the terminals WHILE cranking.

My son's Barracuda had an MSD AND an alternator problem. When it cut out it acted like it was running out of fuel and would not restart, even though it would crank.