Oaklahoma Joes Fire Box Upgrade.

Discussion in 'Side Fire Box' started by created, Jul 21, 2015.

  1. created

    created Newbie

    There are so many of these OK Joe mods threads that I hesitate to make another BUT I believe I have something new to add which can make a tremendous benefit to our cookers.

    I like so many needed a smoker that wasn't going to cost $1000 or more. So in looking for the best of the cheap (on a $500 max budget)... I settled on the OK Joe. Finding the Highlands size more suitable for me needs that what I purchased.

    Before purchasing I read all the various mods the were being made to give greater performance and more predictablity. Sealing seams, sealing doors, Lower exhaust intake, raised coal grate, coal basket, firebox inlet blocks, and tuning/defuser plates. Some of the mods seemed very fundamental, and some seemed half-baked.

    Sealing the firebox to the smoke chamber was fundamental. So was sealing the two firebox halves together too. But I was shocked to see only 4 bolts (two on each end and none on front or back) holding the two halves together. So before sealing I drilled and added the additional bolts to the front and back sides which didn't have any.
    After tightening everything together it was evident how much these were needed. It really brought the two halves together.

    Next was to make a firebox baffle to help shield any infrared heat that could reach the CookChamber. Also serving as a base to start for a tuning plate. I hadn't had any previous experience with smoker building but I understand flow characteristics. The idea being to direct the heat out of the FB and into the CC as efficently as possible. So I set out to make a Baffel design that would be least restrictive in flow. (Note: becuase cheap cookers have such thin wall metal they loose a lot of heat. This makes it even more important to get that heat out of the firebox and into the cook chamber with the least restriction possible. Otherwise it just leaks out the firebox and never gets into the CC).

    I designed my FB baffle with an angle about 65'. Also making sure that it mounted flush with the FireBox hole into the CookChamber. This made for a transition into the CC which was smooth and without turbulence since it mated flush to the top of the CC inlet.
    I then made small winglets that's bolted to the baffel with the conture of the CookChamber walls. Making sure all flow was direct under the baffel.

    At this point I was real happy with my mods. I had planned to make a tuning plate but that was about it. I had my doors sealed and my coal basket made and I was ready to play! Icouldn't wait to season it!

    Next morning coated everything in peanut oil, seasoned it for about 6 hours with briquet charcoal and hickory chunks. All the while checking temps and experimenting with intake settings. I was having a hard time getting it as hot as I wanted. At one point I half over a half bag of charcoal in the FB with plenty of air underneath. I could not get it up to 350' except maybe for a moment on the FB side, but never more than 250' on the exhaust side. I was a bit disappointed at this. But at the same time I knew I had to learn how the cooker worked so I shrugged it off.

    Later that evening I did some chiken leg quarters and still had a tough time keeping heat up. They took twice as long to cook as normally. I had a lot of charcoal in the FB at one point with FB door wide open and still wondered how the temp could be so low in the Cook Chamber. It was starting to puzzle me.

    I came to the conclusion that way too much of my heat was going out the FB before it could get into the cook chamber. This is the problem with all cheap smokers. So I began to think of solutions. I knew if I could just improve the FB then the whole cooker would be upgraded.


    I used 16gauge steel which is nearly the same thickness as the firebox itself. On the FB door I covered as much as I could. The top back half its covered from end to end. the top outer side is also shielded, asweel as the bottom side under the CC.
    On the bottom of the FB I simply rolled the steal to form fit inside. No bolts no spaces but just sits down in there. The only side that didn't receive extra material is the cook chamber opening and the firebox door. Not yet anyways. I plan to double door thincknes and seal the seams.

    I've only done one test so far but the result of insulating the firebox has shown amazing results! I'm beyond pleased! It's showing to be an entirely new beast! I did a 3hr test and was hitting temps of 350-375' on BOTH sides of the cook chamber. And with half as much coals as I was using before! All that and without not needing the FB door open; just using the air vent. Its hard to say exactly how much I increased the firebox efficiency, but it is a lot!

    I'm gonna do some pork loin in a couple days and Ill continue to update my findings. So far the FB insulation has turned this little smoker into a whole new animal and I can't wait for my next cook! this mod is showing to be well worth the effort.
    txbonds likes this.
  2. oldschoolbbq

    oldschoolbbq Smoking Guru OTBS Member

    Nice , thanks for the look and info.

    Last edited: Jul 29, 2015
  3. That looks good.  How did you cut the steel?  Would aluminum work in your opinion?
  4. spenceuiuc

    spenceuiuc Newbie

    How tight was the gap between the insulating plates on the door and on the firebox? 

Share This Page