The Fourth Dynasty of the Egyptian Old Kingdom started with Snefru. The second pharaoh is Cheops, the one of the Great Pyramid of Giza. Then they follow Djedefre, Khafre, Bicheris, Menkaure, Shepseskaf and (perhaps) Djedefptah. Of the kings of the IV Dynasty here we consider the pyramids, to investigate the orientation of their entrances and burial chambers. If possible, the orientation of the sarcophagus is mentioned. The four pyramids built by Snefru show the evolution to the final model with a north entrance and a burial chamber east-west oriented. Then, the pyramids of the Fifth Dynasty are investigated regarding their substructures, which show a coherent orientation. The Sekhemkhet (Djoserty) pyramid of the Third Dynasty is also illustrated for comparison. The position of the sarcophagus and of the body inside is also investigated. In this framework, we propose again what told in 2016, https://arxiv.org/abs/1604.05963