i bought a non running 1990 ford f150, with a blown head gasket, and partially taken apart. i repaired the head gaskets and heads, and put engine back together. it will not start. i have juice , have fuel , but got no spark. the engine just cranks. i know there is no spark from the coil. i pulled the sparkplug wire from the coil i know i have 12 vdc to the plug for the coil. i dont know where to go from there. any help would be wonderful. thanks