I found a New Braunsfels smoker on CL for $50. It's been used 3 times to cook steaks, it was kept outside with a cover then eventually in the garage. The metal is in good shape, no rust holes but the bottom shelf is dented. This thing hasn't been used enough to call it seasoned.
I fired it up and threw in some wood chips to check how bad it leaks and holds temp. I wasn't impressed so I started looking for mods and noticed that this fire box is about 2" higher than some of the better models. So I had to start making changes.
I picked up some 3/16" plate and started marking it out for a lower fire box and a smaller fire box to cooking chamber opening. I used a few of the pit calculators to determine the intake and exhaust opening and if that doesn't work I'll make changes later. I pulled it apart and here's where I'm at right now.
You can see the outlet from the fire box is at grill level and that makes a very hot spot so that part of the smoker is useless, maybe a water pan there would help but I'm going for better results.
I cut part of the fire box top and left that hole to mount it for hopefully a solid seal. I cut off about 5/8" of the top lip to help the heat flow into the cooking chamber.
You can see the ash door with all those leaks, they should've installed some plate inside the fire box to make a better seal but I'll do a temporary fix for now.
Here's the mounting plate, you can see how much smaller I'm making the outlet for the fire box. It's 4" x 9" and should work better with a nice even flow compared to wide open burning charcoal/wood like crazy. When I tested it I used 5lbs of charcoal and it burned for about 2 hours with the temp over 300 for most of that time. I'm sure the ash door leaks had something to do with that.
Here's the new stack I ordered, it's a 4" instead of 3" and should make a nice draw when I mount it on the side instead of the top.
Time to get back to it, my battery is charged. More pics later.