1 Preheat the oven to 325°F. 2  To heat the ham, place it on a rack in a shallow roasting pan, and bake uncovered. 3  For a whole ham, allow 15 to 18 minutes to the pound; for a half, 18 to 24 minutes per pound.4  The ham will be ready when the internal temperature reaches 140°F. Preheat the oven to 325°F. 2  To heat the ham, place it on a rack in a shallow roasting pan, and bake uncovered. 3  For a whole ham, allow 15 to 18 minutes to the pound; for a half, 18 to 24 minutes per pound.