RF Modification help needed

Discussion in 'Reverse Flow' started by brimcconnell, Oct 16, 2014.

  1. brimcconnell

    brimcconnell Fire Starter

    Could use your help from the group.

    Picked up this smoker for what I think was a good deal but it needs some modifications.  It is an RF but the under sized FB sits right below the CC.  The bottom is rusted out a bit so I was going to build a new FB and replace the bottom of the chamber.  My question is whether it is ok to keep the FB in the same location or is it important enough for me to try to totally re-mount the smoker on the trailer and install the FB on the end.  I think there is room to cut it in below the baffle control (seen in the third pic).  

    For information, the CC is 36" in diameter and 68" in length.  Should accommodate a whole pig. I have about 4 weeks for the mods but want to plan it well first.  Any help would be appreciated.
    Last edited: Oct 20, 2014
  2. brimcconnell

    brimcconnell Fire Starter

    Wasn't getting any help so I thought I would add several pictures

    Here's the current FB setup.  The bottom of the CC is rusted out

    It would be difficult to move the entire smoker so that I can install the FB to the end.   Am considering building a new FB that sits behind the CC

    and somehow duct it in so that the FB is not directly under the CC but toward the end.

    FB could go here mounted to steel and still be as far as it is now from he tire

    Any thoughts?  Not opposed to re-positioning the CC but would be less work to put the FB to the back.
  3. lendecatural

    lendecatural Smoking Fanatic

    Is that a 30 gallon drum they used for the firebox? How high above the bottom of the cook chamber is the RF plate mounted? What are the dimensions of the cook chamber?

    Here is an online calculator that will help with the firebox dimensions: http://feldoncentral.com/bbqcalculator.html

    Read this thread about sizes required for the firebox, cook chamber openings, and the calculator: http://www.smokingmeatforums.com/t/161795/is-feldons-calculator-really-flawed

    This smoker is what I think you really want to end up with except yours is facing 180 degrees: http://www.smokingmeatforums.com/t/108670/center-firebox-rear-facing-reverse-flow-trailer-build
  4. brimcconnell

    brimcconnell Fire Starter

    Thanks Len. I've run Feldons. Not sure what size the existing FB tank is.  Overall CC size is 36" x 68"  Bottom of the barrel to the RF plate is 10". The link you shared is along the line of what I was thinking.  Seems like my idea may be ok to continue to engineer.

    Link to BBQ Pit Calculator
  5. lendecatural

    lendecatural Smoking Fanatic

    For a center firebox, the 1.5 isn't as critical. The factor really comes into play with a long skinny tank since there is so much friction loss over long distances. You may want to look for tank like SouthOfManitoba used, it will take a lot of welding out of the project. Your 10" RF plate height will work well.
    Last edited: Oct 23, 2014
  6. Are you wanting to keep the center FB or fab a new and larger one and move it to the end ?

     you have 69,216 cu in    fIre box should be a minimum of 23,049 cu in  I would go at least another 15 TO 20 %

  7. brimcconnell

    brimcconnell Fire Starter

    I don't want to move the whole thing on the trailer so my question was if it was ok to build a new FB on the back side, kind of like a center FB but it would be closer to the end and have a plenum for the smoke and heat, rather than being directly underneath the CC. From earlier comments it seems that may indeed be ok, with the sizes you mentioned.  That way I can leave the CC in place. There is plenty of room on the rear end of the trailer to build the new smoke box and not get too close to the tire.

    Thanks for the help.  Keep bringing the great ideas.

  8. I personally have never done a center firebox but I have seen several post that have.  I guess my question is are you going to have the RF plate open at both ends ?   On an RF smoker you need smooth air flow controlling the temp with the dampers on the forebox

  9. brimcconnell

    brimcconnell Fire Starter

    This won't be a true center FB. My intention is to use this as a RF.  The RF plate is only open at the end opposite the stack.  I want to mount the FB as close to the stack end as possible, just on the back.  How do you think this will effect the airflow?  I would like to get consensus on whether this will work. 
  10. brimcconnell

    brimcconnell Fire Starter

    Well, I gave up trying to build a firebox to fit the existing layout so I decided

    to re-mount the CC and built a new FB on the end of the trailer. More pictures to come.

    Plan to smoke a hundred pound pig this next weekend.

  11. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Your smoker is looking good.....

    For ease of fire/temp control, and reduction in fuel usage, think about the air inlets to the firebox.....

    Last edited: Nov 9, 2014
  12. brimcconnell

    brimcconnell Fire Starter

    I have vent holes in the sides now, at the bottom.  I am struggling with the vents for the door but may end up doing like you did.  Will post more pics when I get finished.  This will be finished soon as I am smoking a hog next weekend for my daughters 18th.  Trying to figure cooking time for a 100 lb hog, head on, racer style with this rf smoker.  

    Last night I also cut in a butterfly type vent high in the door.  
    Last edited: Nov 10, 2014
  13. brimcconnell

    brimcconnell Fire Starter

    Well, not nearly finished but it will smoke. I messed up my butterfly vent but will modify that soon.

    Will be smoking 105 lb hog this weekend.  Wish me luck.
  14. Nice out come mate. Yea I could imagine the head f it would have been to try and mount the fb under the cc. So many angles.
    But is looking good.
    Your butterfly valve is different I give you that.. Personnelly I'll be sticking to opposing 1/4's of a circle. Much easier imo.

    And good luck with the smoke.
  15. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Nice job.... That will work.....
  16. brimcconnell

    brimcconnell Fire Starter

    Well, Pig roast went great.  It was a long, extremely cold night, down in the 20's around 2:00 AM.  Didn't get a lot of pictures but here are a couple.  Pig turned out fantastic but keeping the heat all night was miserable.  Not sure if I did something wrong or if I was just fighting extreme cold. Final time was 18 hours keeping the heat as close to 220 as I could. Daughter loved her party and her pig.  

  17. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    I'll bet it tasted good...... Wish I had some....... :drool

  18. Man that turned out nice !!!   I'll bet it was terrific 

  19. brimcconnell

    brimcconnell Fire Starter

    Thanks.  It was tasty. First time smoking on RF offset.  Smoked on oak all night with some lump hardwood charcoal to keep the heat up.  I think I missed something with the air control.  Should have built a larger fire and then toned it down by reducing airflow?  I tried to keep the fire small and still use the air vents and it was just a lot of work.  I think I will try something less Whole hog next time like a fatty and a brisket.
  20. Doing a pig for your first smoke on a new smoker was pretty ambitious glad it turned out, and everybody enjoyed it. I tell people who are smoking for the first time or on their new build keep it simple, chicken and sausage are cheap, pork shoulder is hard to mess up, start with these to get your smoker dialed in and you comfortable with how it performs. Gives you time to figure out fire size, damper adjustments, how long and when to add more charcoal or splits.


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