300 Gallon offset smoker Help

Discussion in 'Smoker Builds' started by fisher6688, Sep 15, 2014.

  1. Alright so i got a 300 gallon smoker that was already made. i did the calculations on the calculator for size of FB and size of chimney. 

    The firebox is at about 76 percent of the preferred size according to the calculator. 

    i am having trouble because the chamber is getting too hot. i have a couple splits going and i cant get a spot on their thats not over 240. 

    Should i get a sheet of steel and block some of the opening to the chamber from the firebox like a damper?
    Last edited: Sep 16, 2014
  2. edited
    Last edited: Sep 16, 2014
  3. i have already tried to close some of the inlets on the FB but if i close it too much flame goes out and im getting thick smoke. 
  4. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

  5. Here are the specs. 30 inch x 78 diameter smoking chamber. Fire box 19x24.5x30. Two air inlets on both sides. Chimney 5 inch diameter and 40 inch long. Goes down into the chamber about half way. The firebox opening to smoke chamber is 21 inch at its widest (half moon sort of) and 6 inches down. I'm posting pics now. Thanks for any advice Dave
  14. i tried using some of those grates lower than intended to see if it gave me a a little cooler temp since heat rises. And yes i am wanting to get some temps below 240. Also be able to do this with a nice small hot fire in the firebox. I found that to get the small hot fire you need to have the inlets opened up to get the oxygen in there. when i try to close a little to make it less of an opening it kills the flame and i will get thick smoke. 
  15. judging by this calculator http://www.feldoncentral.com/bbqcalculator.html

    my half moon opening should have been 16.87 inches in diameter. so i took my measuring tape and measure where 16-17 inches diameter would be on a 30 inch diameter pipe. it ended up being only 2-2.5 inches in height. so is it possible that im getting really hot in the smoking chamber because my opening is around 21 inches wide with a height of 6 inches?
  16. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    OK... good pictures..... your smoker is a SFB and needs tuning plates.... the opening between the FB and CC should NOT have that flap thing... the opening needs to be "opened up" larger.... The exhaust needs to be cut off inside the CC.... maybe 2-3 inches below the top of the CC.... The tuning plates must be above the FB/CC opening.... fit tight to the side walls of the CC... and extend to about the welded seam on the tank... spacing is tunable for even heat distribution to the cooking rack, or what ever heat you want at the cooking rack...

    Unless, of course, you want some sort of "Jambo" halfbreed clone...

    Some serious measuring and thought will be needed BEFORE any cutting and welding... That's a nice looking smoker... It can be salvaged into an awesome smoker....

    Now we need to know what type of smoker you want and how much you have to spend... SFB or RF... reverse flow...

    I would stick with the SFB... that will not cost much...
    Last edited: Sep 17, 2014
  17. Thanks for looking dave. I want to keep it SFB. I actually like the different temp zones. i usually cook different types of things at the same time. for example, i would like to throw some chicken legs or quarters or wings near the FB where it is hotter. And i will be doing things like veggies, corn, pork butt, brisket, ribs on the far end where it is not as hot. i just traded for this smoker so i did not have to put out any cash. i just wanted a bigger smoker to do different things at once. i also wanted a bigger one because i wanted to throw a couple splits in the FB with my meat further away from the 

    So is it possible to damper the heat a little bit more without the tuning plates? or how would the tuning plates help with keeping the far side a little cooler, hopefully so i can peg a temp of 225-240. 

    Should i do anything with the size of the opening from firebox to the CC? is it possible to leave the flap instead of having to cut it?

    What will cutting the exhaust do?

    Does Keeping the grates at halfway or higher than midpoint on the CC have any benefits than having a rack thats lower than that

    Sorry for all the questions. 
  18. oldschoolbbq

    oldschoolbbq Smoking Guru OTBS Member

    Tuning plates...I think they are Marvelous [​IMG]

    have fun and . . .
  19. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Below is what you need..... All the above notes from members and myself, are great suggestions....

  20. Thank you guys for your help!

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