The woodruff key on the distributor gear may be sheared or your rotor is defective. Before installing the distrubutor you need to get No1 piston near the radiator to TDC on the compression stroke. Pull No1 sparkplug and hold your thumb over the plug hole while a helper slowly cranks the engine. Once you feel pressure drop a long plastic straw on top of the piston. Then you watch the straw rise as the helper slowly cranks the the engine. When the straw quits rising your No1 piston should be at TDC on the compression stroke. Rotate the rotor until it points to the No1 plug tower which is about 1 o'clock and install the distributor. Hal
PS: Firing order:
4-3 As the rotor rotates CW.