Brake Bleed Issues

Problem bleeding brakes after replacing left/right front calipers, lines and pads. I changed these items due to a "brake failure". I was able to pump the brakes to get the right front to grab but then had to "baby" it home where I changed the above items. When I try to bleed the brakes, the right front and the left aft bleed fine but the left front and right aft seem to have massive amounts of air with no associated "pedal-drop" when the bleed valve is opened with brake pedal pressure applied and held. I have disc brakes in the front and drums in the rear.