Reviving this thread to say thanks to everyone who contributed. I was planning to do my first brisket today using the old low 'n slow 12-14 hour cook until I did some research and came across this thread. I'll try to recount my experience so maybe someone else can try this with confidence ('cause I did some things different, and not on purpose).
Started yesterday by doing a light trim on a 9 lb packer. Rubbed with a little veg oil and with my beef rub concoction. Started getting the grill ready today at about 11:30 am. Filled my ring with K and put 30 coals in my chimney. Lined my pan with foil (no water). When the chimney was ready I added it the ring along with a nice size chunk of apple wood. Assembled the smoker and put the brisket on. I stuck a probe in the meat and let my grill probe dangle just inside the lid vent. All vents wide open. Here is the chronology of my cook:
12:05 Brisket on. 155/50 (smoker temp, meat temp)
12:20 236/54
12:35 283/63
12:50 327/73
1:05 315/82 Before this reading the smoker temp got up to 335 so I closed 1 vent and closed another vent half way.
1:20 316/90. Opened the vent that was half open to 3/4 open.
1:35 328/99 Opened the 3/4 vent all the way.
1:50 333/110
2:05 330/120
2:20 327/131
2:35 321/143 Opened the vent that was closed all the way.
2:50 325/151
3:05 328/159
3:20 321/164 At this point I foiled the brisket and removed the temp probe. Left a little room in the foil. Didn't add any liquid.
3:35 323
3:50 290 I added fuel before this reading but I couldn't keep the temp up.
4:05 290
4:20 290
4:35 289 Checked for tenderness. Opened the foil and released a ton of steam. The smell was incredible! Temp probe slid in and shot up to 190. Looked done to me so I took it off and brought it inside to rest with the foil still on.
The reason I think the cook took longer than some other HH cooks is that my temp was lower. The probe I had just inside the lid was reading about 20-30 degrees higher than the built-in gauge. I couldn't really get the temps to rise but since the meat temp was going up consistently I wasn't worried. I was a little concerned that after I foiled the temp was way lower than I wanted but it still came out great.
While the brisket was resting I made the #5 sauce. Pulled some liquid out of the foil to add to the sauce (used a fat separator). Sauce was awesome! After resting 45 minutes I sliced and we made some sammies on hot cheddar rolls. Outstanding! The meat was juicy and there was a nice smoke ring. It came out great so thanks again to everyone who contributed to this thread. I couldn't have done it without you.
Lets see if I can get some pics up: