Be sure that the distributor shaft engages the oil pump. There are a couple of ways that the oil pump can be aligned with the distributor shaft after you have determined that number one is at TDC on compression stroke and where you want the number one plug wire to come out of the distributor. The first is to line up the rotor on the plug wire for number one and take a screwdriver and align the oil pump so the distributor shaft will drop in. The other is the same except you crank the engine over until the distributor drops in place.