Knowing what type smoker you have could be of help. However, I do briskets in an electric, at 225 degrees to an internal temp of between 195 and 200, preferably 200. It should jiggle like jello when done. I then remove from smoker, double wrap in heavy foil, wrap that in a thick towel and place in a small cooler till ready to serve. The cooler keeps the meat hot for several hours. By the way, when doing brisket, or even a butt, the meat temp will stall around 160/170 degrees and seem like it will never move. Be patient.