Originally Posted by IMA_Redneck
Those pipes are 12" long 1/2" pipe nipples each has 4 1/4" holes cross drilled in it. 3 have pipe caps on them on 1 has a ball valve. Seems to work very well. In fact it may work too well. I am having trouble getting grill temps below 300. If i measure near the edge of the barrel I read 225-250 but over 300 right in the middle below the grill. The pipes fit very tight in the holes i drilled but i am going to try silicone around the holes to see if i am getting air leakage there. It may not be a big deal either way because it still makes great Q.
You're going to get some variation in temps, since the drum basket rest in the middle. That's where you want to judge it by, but you should be able to pull that down w/ the ball valve if you don't have any additional excess air leaks.
Other way to deal w/ the temps inside, is a diffuser.... This one has been debated often, but I for one have found it very useful for me. Does use a little more fuel typically, but it will help keep the middle of cooker a little more controllable. Next question is usually what to use, and again, various methods, but most commonly used is a large pizza pan with holes, slots, etc cut in it. Then there is SmkKing that makes us all jealous with this water jet cut diffusers....
LOL!! (Sorry dude, had to throw that one in there!) Look back in this thread a few pages, and I'm sure you'll see his and know it right away.... as well as others....