I don't think I've posted this directly here before...I do know I've linked to the original on another forum.

Here is a series of pics from a few years ago when I converted my woodburning (and uneven-cooking) New Braunfels smoker to run on propane. This was originally posted at thesmokering.com:

I've had a New Braunfels Black Diamond (NBBD) for about 10 years or so, and although I've liked using it, it's always been hard for me to maintain a steady temperature. I've had a tendency to oversmoke and/or overcook the food I've cooked in it and the temps in the cooking chamber have always been pretty uneven, with a wide range from one side to the other.

In an attempt to fix these problems, I made a few mods. I added a deflector between the firebox and cooking chamber, a Horizon convection plate, a gas burner from a turkey fryer, a grate for the lava rock ballast for the burner, relocated the thermometer, and extended the smokestack to just above the top of the grate in the cooking chamber. I hope you guys like pictures, because I brought a few for Show and Tell.

Here's what I started out with. Plain stock NBBD. You can see the gas assist line coming out of the firebox. It's made to attach a camping-style propane bottle, but it never impressed me, so it's been unused for years.



Years ago I got tired of dealing with the dinky screws that were supposed to hold the cooking grates in place, so I added a couple pieces of 5/8" all-thread. You can also see the stock opening between the firebox and cooking chamber. According to Tom C's Pit Ratio Calculator, the opening is more than twice the size it needs to be.



The all-thread is simply bolted through the ends of the cooking chamber and tensioned...



Here's another couple shots of the factory gas assist setup. From the outside...



And on the inside...



First order of business after removing the firebox was to drill a hole for the turkey cooker burner. It's 2 3/8" in case anybody is wondering...



After doing that, I hit the firebox with a wire brush and some high-temp paint to touch up a slight bit of surface rust. While the paint was drying, I cut and bent a sheet metal deflector...



Then I slipped the convection plate into place...



I hadn't drilled the holes when I took this pic, but two of the firebox bolts will go through the deflector to hold it into place. Here's how it ended up looking from the cooking chamber side...



While I was working on the cooking chamber, I added a short piece of 3" flex duct to the smokestack...



I also moved the thermometer so it's a couple inches above the cooking grate. (No specific pics, but you can see the new location in some of the other pics below.) While I had the thermometer out, I checked the calibration and found that it was reading about 45 degrees hotter than it should. I have a 3" Tru-Tel on order to replace it.

Then it was back to the firebox. The burner has a threaded stud on the bottom. I drilled a hole for this stud through the bottom of the firebox (and the firebox liner), placing the hole so as to leave the orifice end of the burner flush with the outside of the firebox...



And I ended up with this...in this pic I'm doing the first test burn after leak-checking all the gas fittings...



I needed a 14" x 16" rectangle for the ballast grate frame. I don't have a welder (or know how to use one, for that matter), so I just notched and bent some 1" angle iron. (Had a little help from a propane torch.) Since the expanded metal I had was only 12" wide, I needed something to bridge the frame to hold it up. Turns out the original grate that went in the bottom of the firebox fit just fine. In these pics there is only one grate, but I ended up adding a second one since I had it laying around..



Add a piece of expanded metal...



And some lava rocks for ballast...



And here's how it looks through the firebox door...



Time for a test burn. The fryer burner is more than capable of getting the cooker up to temp, and with only a bit of playing around with the regulator valve, I was able to get it dialed in at 250 degrees pretty easily. (The valve is barely cracked open at that temp, so it's not using much fuel.)



So I had heat, but I still needed smoke. I have a stainless steel box that was made for wood chips on a gas grill, and it happens to fit handily under the ballast grate. Sitting next to the burner and getting radiant heat from the lava above it, it didn't take long for a few hickory chunks to start burning.



The end result: The fine blue smoke I keep hearing about...



Time for a test drive...



A couple hours later...



And about four hours after that...



All in all, I'm very happy with the results from the mods. The temperature variation across the cooking chamber is now only 2 or 3 degrees, instead of about 40. Since I'm not relying on wood or charcoal for my heat, I have better control over the amount of smoke the food is getting. For the first time ever, my ribs have the right amount of smoke flavor, and no hint of creosote flavor. And aside from adding wood chunks, there's no babysitting required to keep the cooking heat steady for all-nighters. I'm a happy camper.

I haven't done it yet, but I plan to replace the shelf that's attached to the front of the cooking chamber. I'm much more of a woodworker than a metalworker, so I'm going to try to come up with something a bit nicer than what comes from the factory. I also intend to beef up the shelf underneath the cooking chamber to better support the propane bottle and keep it in place. I may also replace the wood in the handles with something a bit nicer. (I've got a bunch of nice hardwood scraps, and a lathe.)

Well, that's my adventure in cooker modding. Comments and suggestions are welcome. You can even tar and feather me for the sacrilege of adding a burner to a wood-fired cooker. I'll just be sittin' over here eating me some ribs. :P

...

After that write-up was posted, one of the Smoke Ring regulars volunteered to make me a custom fitting for the grease drain at the bottom of the cooking chamber. The fitting has a short threaded nipple so I was able to attach a 1/2" ball valve. It works great. (I sent him a curly maple cutting board in exchange.) And I still haven't made new shelves for either the front or the bottom. (Not in a hurry to do so either, seeing as how I haven't had a chance to use the smoker in over a year and a half.)