Originally Posted by DJ's left nut
To clarify what I'm sure FMB meant, if you close down the vents, ONLY CLOSE THE BOTTOM.
The top vent stays open at all times, regardless of temperature. If you really want to ruin a piece of meat, close up the top vent. That smoke will just sit on the meat and give you a creosote buildup from hell.
Yes, of course. Should have mentioned, you actually want to position the top vent over the brisket to keep smoke flowing.