If you still have smoke at 7 hours, let it go. No more wood. Actually, 7 hours of smoke is a lot of smoke. Just don't over cook the ribs. My baby backs are generally done between 5 and 5 1/2 hour. You should check on them and pull when done. The butts are going to take more time. Are you smoking the butts to a particular internal temp? I pull mine at 195 degrees internal.
