Originally Posted by kevine
Used my UDS (built in early Jan 2012) for the first time on a long cook. Been doing mostly moink balls and ABT's on it, but did a pork butt for Superbowl. Not only did it cook a little faster than my old offset, but it held 235-240 perfectly even for close to 10 hours. I finished an almost 8 lb pork butt in about 9.5 hrs. I opened it a couple times to spray with apple juice, and it dropped to about 215. Within 30 seconds of removing the caps off of the other three intakes, it started going back up quickly. Capped them back off and it just kept on cruising at 240
MAN I LOVE MY UDS!!!
You shouldn't really have to give it more air after you take the lid off. In fact the opposite should be true.
If you think about it, before you take that lid off, you only have a very small amount of combustion air coming in through your intakes. When you take that lid off, the fire gets a huge gulp of combustion air (by comparison). It will burn through that air hotter than if you had not taken the lid off.
Your temp gauge drops only because there's some cool air in there at the moment, but the fire isn't running at that new cooler level, it's still hot as it was and even hotter now due to the extra air.
It will easily catch up on its own. In fact, I think most drums will actually run up in temp after taking the lid off. Many turn their intake air off before taking the lid off to prevent too much air from getting in and causing a temp spike.