cook in a 425 degree oven for 15 minutes. then reduce the heat to 325 for the remaining cook time. cook for about 15 minutes per pound. a 3 pound roast will need about 1 hour total (45 minutes more at 325 degrees) and a 4 pound roast will need about 1.5 hours total (1 hour, 15 minutes more at 325 degrees).