250L build - now a 35? gallon build

Discussion in 'Reverse Flow' started by munxcub, Jun 20, 2013.

  1. That's right, 250L, not gallons. 

    It's an old auto propane tank, it's ~85 gallons water capacity. Measures 18" diameter by 80" length. 

    A few questions.

    Based on the calculator I have come up with a 20"x20"x20" fire box. Gives me %118 of the recommended firebox size, I figure a little bigger cant hurt. 

    Will having a cube be detrimental in any way? I like that it will be an inch wider to either side than the tank, has a nice symmetry. And being a cube pleases me as well, but most/all the builds I've seen on here were not cubes. 

    Do you think there would be room for a 2nd cook rack in a tank of this diameter? I'm not really thinking it's likely, but maybe a removable one for some low profile eats, like ribs or something. 

    Pretty stoked to get going on this. I will have the tank the weekend of July 6th, so will get to work on the fire box and rough in the legs, wheels, etc.  So when the tank arrives most everything else will be done. 

    That's the plan anyhow, and we all know that no plan survives first contact... haha

    Have my first BBQ contest Aug 10/11 and need a bigger rig if I want to compete in more than 1 event.  So the clock is ticking. Will need to build it, test it, and learn it before then. Lots of time, right? ha!
  2. Ok, I started drawing it up and figuring some stuff out. According to the calculated size of the opening of the FB to CC my RF plate is going to be about 2 3/4" off the bottom. Is that way too low? It would be nice if that's correct as It would leave me room for 2 cook racks with about 6" between the bottom and top rack, and the top rack and tank.

    ETA: About the fire box, if the calculator came up with 20x20x20, do I need to add any more for the air intake vents, etc? Or is that the size of the box, and then cut the vents, and put in a basket/rack to put the wood on, etc?
    Last edited: Jun 20, 2013
  3. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Munx, morning and welcome to the forum......   Sounds like a great smoker build.....  Below are the numbers I came up with for your design...   The FB can be built larger than the recommended in the calculator... no adjustments are needed.... Weld the RF plate to the top of the FB...  cut out the FB for the CC opening at the same radius as the CC....   To reduce the heat on the top of the FB and the first section of the RF plate, a heat shield can be installed...  see other drawing for that....   The numbers below will allow for great heat/smoke/air flow through the CC....   the exhaust stack height is figured from the top of the cook chamber...  make it longer to attach just above the lowest cooking grate.....  See the drawing and ignore the numbers..... they are from another build....  Any questions ?? Many folks on this forum are knowledgeable in smoker builds and can help you make the best smoker in your neighborhood...  

    Hope this helps with your build....   Double check the measurements of your tank (cook chamber) before you start.... they are the basis for all the calculations....    


           ....  click on pic to enlarge .....

       .... click on pic to enlarge..... 

    munxcub likes this.
  4. Wow Dave thanks! I didn't expect anyone to do my homework for me. I wasn't too far off with my sketch last night, but I did notice you have the FB set pretty much halfway in. 

    The 18"x80" for the tank was off a spec sheet my brother-in-law provided, and I assume it's the exterior dimensions.

    I'm hoping to get the FB done before I get the tank, just so the project is moving forward. If the measurements are the exterior dimensions, that would make the FB and vents slightly larger than recommended. Would that cause issues?

    the 4 sq in intake towards to the top of the FB, is that more to vent off some heat if it's getting too hot?
  5. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    All the work isn't done  yet....    Check the dimensions....   Inside dimensions of the tank will be necessary for a proper fit of the RF plate...    Draw the smoker on paper to make sure it all works....  changes on paper are easier than in steel....   

    In my signature line are calculators that make life easy.....  

  6. You bet, thanks Dave! I've been kicking it around in my head for days, and have played with the calculator quite a bit already. 

    I'm confident that I can start building the FB while waiting to receive the tank. I will hold off on the RF plate until the tank is in hand, and cutting the FB-CC opening as well. 

    Pretty excited. I'll be sure to post pics and whatnot as I go along. I appreciate the help so far, and all the information that I've read around here so far. 

    The internet is a wonderful thing, would never have thought to try this, or restore old cars without it. heh
  7. Is it necessary or just nice to have the adjustable baffle/door between the FB and CC? I suppose you would reuse the piece that you cut out for the opening in the FB... Just trying to wrap my head around all the little touches it'll take to finish off, and what materials I'll need. 

    Also trying to figure out what the bare minimum would need to be done on it in order to cook, as opposed to all the nice to have bells and whistles. Just looked at my schedule and there are not a lot of weekend between now and the contest, and my wife has a decent sized list of tasks/projects for the back yard for this summer.

    ETA: if there's an FAQ/checklist type thing I missed on building RF smokers in general, I apologize. 
    Last edited: Jun 21, 2013
  8. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

  9. You're the man Dave. I might have to name it after you when it's done. 
  10. Well back to the drawing board. My brother in law's boss wants like $200-300 for the old tank.  But my dad just texted me saying he found me a free 60 gallon air compressor tank. Going to check that out. The price is certainly right. Stay tuned for updates.

    In the meantime, here are some pics from the weekend. All this research about RF smokers and I had to fire up my WSM

    This is one of two that came out (had pics of the other and the full green bowl, but my phone decided to corrupt those ones...) Just under 17.5 hours. Was drizzly and cold, put them on at 9:00PM Saturday night and they came off around 2:30 the next afternoon. Wrapped in foil, parked in a cooler with towels and pulled about 3 hours later. Still plenty hot. Tried Soflaquer's finishing sauce (I think I spelled that right...) I was just telling my family that the last few have been pretty consistently good, and each one was better than the last. These were the best yet. Not sure if it's the finishing sauce or the extra 2.5 hours that they took to get to temp, but it was damn fine. 
    Last edited: Jun 25, 2013
  11. smokejumper

    smokejumper Smoking Fanatic

    If you weren't in Saskatchewan, I'd be up there in a heartbeat for some of that! [​IMG]
  12. So, if I wanted to spend my long weekend building a fire box, but don't get my 60 gallon tank until next week, do the dimensions of the CC matter for firebox size? Or just the volume? Or should I be trying to get ahold of the tank sooner than that to get the dimensions?
  13. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Munx, morning....  Wait till all the pieces are there....   See post #3... You need to know the diameter of the tank in order to build the firebox.....   Draw everything on paper first... recheck dimensions and fitment...  changes on paper are very easy..... changes in steel are a PITA, time consuming and expensive...

    Trying to get ahead now could be putting you behind later...... 

  14. Dave,

    I know that's the right answer. I think I was just hoping to confirm what I wanted the answer to be (start building stuff this weekend...) heh.

    Maybe I'll see if I can pick the tank up before the weekend instead of him dropping it off early next week.
  15. Just call and get the width, then you can start building the firebox.....Or just drive and go get it tonight!!!!!
  16. Yah sounds like a plan. Seems like any I find online have the same dimensions. But I'd rather just get. A long weekend might see it finished enough to try out. Heh
  17. Just dont rush it, take your time and build it right and it will last you a lifetime.  Nothing wrong with eating at BBQ joints until its ready, or letting your wood season really good.
  18. Well I still have my WSM and propane cabinet... Heh
  19. Nothing wrong with that, Id take my time and make it perfect then.  Im doing that right now myself, no expense spared, only top notch material and not rushing it. Its going to be "my smoker"  and every little detail is going to be perfect.
  20. Yeah I agree with not rushing it and making it right. My only reason for wanting to get right into it, is that I want to enter a contest beginning of August and need to have it finished, tested and learned by then. Not many weekends left between now and then, and to lose a long weekend (Monday is a holiday up here) would be a real shame.

Share This Page