First of all you will need to preheat the oven to a temperature of 375ºF (190ºC). Roasting a chicken does not take quite so long as roasting a turkey, however a large chicken could still take over 2 hours to roast.As a general rule, calculate a cooking time of 20 minutes per pound of meat plus an additional 10 - 20 minutes at a temperature of 375ºF (190ºC).irst of all you will need to preheat the oven to a temperature of 375ºF (190ºC). Roasting a chicken does not take quite so long as roasting a turkey, however a large chicken could still take over 2 hours to roast.