The temperature should be 165 F. How long it will take will also depend on the size of your bird. I find it takes about 90 minutes in a 375 F to cook a 2-3 pound chicken. I notice that Safeway always sells whole frying chickens, but we roast them in the oven.I believe the fryer part refers to the size of the chicken. find it takes about 90 minutes in a 375 F to cook a 2-3 pound chicken. I notice that Safeway always sells whole frying chickens, but we roast them in the oven. I believe the fryer part refers to the size of the chicken.