What a thread,eh?!
If you can't find it here, it can't be found! I've built two, here is what I have learned:
The first got a Weber kettle lid. When I cut the top of the drum to accept the lid, I was never able to get a cut plum enough to make a good seal ( I am not sure if it is the drum that is not cut perfectly or the lid itself is out of plum). This drum has 4 1 inch tubes welded in as vents. 1 has a ball valve, and 1 has a mount for a guru.
This drum is fairly jumpy in the temp department, and I am sure it is the seal of the lid-I can put the lid on one way, and the temp drops. Another way and temp goes up. Add the variability of the ball valve and I have a unit that requires a decent bit of babysitting. It is a bit more stable at higher temps, so chicken and the like do better on this one than say pork butt.
So I built a second, and went as old school as I could.
Three 7/8" holes with plugs. 1 rack 24 inches from the bottom of fire basket and the regular drum lid with a good tight seal. This lid had two bungs on top- a 1.5" in the center and a 2" off to the side. I threaded a 1.5 ", foot long pipe in the center hole.
With that setup, the temps dropped steadily with one vent open, and ran around 300 with two open. Soooooo, I lost the small pipe in the center and got a 2 inch for the side bung (got a 90 deg for the top for rain also).
Eureka. One intake open is a little under 225 and steady, 2 open around 275 or 280 and steady. El perfecto. Runs just like a BDS-a little hot, but it is a different kind of cooking technique. Love it. Since it is now very consistent I think it will be a real hoot to put the guru on it (choke down the exhaust), but not at all needed.
The difference between the two drums is the consistency of the airflow.
So the next project:
I really want to get the kettle top thing figured out to have a usable 2 decker. Step 1 I want to try to get a perfectly level cut on top of the drum (I think I have 1 more chance at that before the cut gets too close to the "rib" of the drum and the lid on longer fits), and get that seal a bit better. If not, that drum goes on the scrap heap, and another flattop will be born. Maybe that will be a double decker.
I woulda gotten away with it if it weren't for you meddlin kids and your dog!