Something is off. I do rotis chicken on my kettle with coals on one side and st a kettle temp around 325 or so and it takes on average about 1.5 hours. Top vent open above chicken opposite the coals. Also make sure to cover all unused space of the coal grate with foil so fresh cold air does not mix with the heated air. If you don't use the cover then coals should be very close to being under the chicken. This applies to almost any meat you are cooking. Other ways require differant applications.