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Oklahoma Joe Longhorn size questions

post #1 of 46
Thread Starter 


First post.  Been reading a while and lurking.  Finally joined.


Just bought an Oklahoma Joe Longhorn from Lowes.  I would have loved to have a Jambo, Lang, etc. etc., but I just can't afford it.  This OJ is as much as I can afford.  


I've already sealed the doors and seasoned it.  Also built a firebox.  Looking to do a 45 degree plate on the firebox to cook chamber inlet to help with the heat there and also looking into the best way to get the exhaust stack down to grate level at least. 



My questions come out of using the smoker builder calculator.  When I input the measurements for the cook chamber and the firebox I get some concerning numbers. 


The firebox comes out at around 135% of the optimum size.  Okay, probably not going to build a whole new firebox.  BUT more concerning is that as close as I can calculate from actual measuring, my air inlet is right at 7.5 square inches.  The calculator shows more like 15 or so square inches required.


Also, the calculator is showing that the opening from the firebox to the cook chamber is too large and that the exhaust vent is too short.  As close as I can measure my exhaust it is approx. 9 to 10 inches short.


So, the biggest issue to me is the inlet on the firebox.  Basically it is half the size of what the calculator specifies.  What has anyone done to cure the inlet size to allow more air?  Any tips or pics would be appreciated. 


Now I've got the OJ I'd like to optimize what I have at least and this inlet size looks to be a real deficiency.


The firebox to cooking chamber sizing I can probably adjust with the plate/deflector I plan to put in.  Also, the pipe length issue will probably be taken care of with extending the pipe down to the grate.  So, really it is just the inlet that is a big concern.


Thanks for any help.  I did do a search before posting.  If I missed where this has already been covered please post a link to the thread. 



post #2 of 46
Thread Starter 

I'm adding to this post for anyone as anal as I am on this stuff.  It probably makes no difference as I've not seen anyone else talking about it and they seem to be cooking fine, but I know me and my lunacy it would bug me without trying to do something about it.


I've been looking at posts others have made about their OJ Longhorn and have seen pictures where their inlet door on the side of the firebox is different.  They have a round inlet adjuster with two holes rather than the single triangular one I have.  Don't know if it is a deal of where the grill is purchased as I have seen the round two hole inlet adjuster type at Home Depot and Lowes carries the single type.  I did not bother to measure the HD one to see if it was the same 40" cook chamber etc. or not.  Either way, with the measurements from my smoker the smoker builder calculator says that my inlet size is half of what it needs to be. 


I put graph paper behind the inlet with it full open and traced the opening.  A square inch on the graph paper is 16 boxes.  Calculating out I came out with approx. 7.5 square inches of vent stock. 


I looked at various ways of increasing the inlet area and then I had a bit of a brain storm (well, more like a light drizzle than a storm).  The way the existing damper is designed, when you open the adjuster all the way the adjuster handle hits the side of the opening long before the damper is fully open.  I took the damper off the inlet and measured the total space on the inlet available using the old graph paper method again.   Much closer to what I needed. 


It also looked to me like the damper was not a straight triangle (don't remember the geometry term, is it right triangle?) either.  So what I did was cut the existing adjuster handle off so it would not hit my firebox grate or box, flip the adjuster over and remount it.  I then opened the adjuster all the way leaving just enough of the damper visible to put a nut and bolt through for a new handle.  Ended up that the adjuster handle was going to be closer to the top rather than the bottom, but works fine.  I made sure it would close off the firebox inlet when I wanted to close down the grill and marked, drilled and put a 1/4 bolt through it.  Works great! 


Not got the 15" inlet that the calculator said I needed, but the old graph paper measure calculator put the inlet now at a smidge over 12" of area. 


So might be wasted/futile exercise, but if anyone else has the same grill and thinks they may have an inlet starvation issue, here is a cheap thing you can do to maybe get you there.



post #3 of 46
Hi bud
post #4 of 46
Hi bud Don’t worry about that opening!! Mine cooks just fine the way it is. What I did to help airflow was to raise the firegrate. Do this by taking the coal grates from the smoke chamber out. Put them in the firebox, but turn them 90 degrees forst, then you can lay them side by side in the firebox. This raises the fire in the box and it breathes much better. I take the 3rd grate and lay it the other way on the other 2 to make a square pattern and it helps hold the small coals. I can cook for hours and hours like this, no modding any of the vents.
post #5 of 46
Thread Starter 



Thanks for the post.


Is your OJLH the kind with the single triangular vent?


Thanks for the tip on the firebox.  I'd already done the same except I'd not laid the third rack across them as I made a couple of baskets.  One for charcoal that has an S pattern to try and extend the burn (minion) and one that is just a square that I can throw a chimney of charcoal in and then start throwing splits in.  Only issue with either is you have to use the top door to add to the fire as the basket blocks the side door.  Might consider an open end one for the wood splits and see if the side door can be used just so I can hold heat.


Apart from the calculator bugging me with numbers that don't match the smoker, I had a pretty hard time getting the grill hot to season it.  That prompted my looking into the design and the calculator.


When first got it I used charcoal and wood to try and season it.  Did not have the baskets then.  Just tried to keep everything where air could get to it and together not spread out.  Had the exhaust vent full open, inlet adjuster full open.  90 some degrees outside and just a light breeze.  With the junker gauge on the lid, the smoker going full bore, I could barely get it to 340 (once).  This was with the wind blowing to the inlet side and me finally using cardboard to fan through the inlet to stoke the temps up.   Most of the time it sat at 275 to 310 ish.  Comparing to the probe I had on the grate the gauge was an average of 72.5 degrees off (too high). 


It also used a lot of charcoal and wood to get it there. 


Next few days I tried different empty simulated cooks.  Nut shell, the exhaust end (tried with and without my dryer vent extension to the grate) would hover around 190 to 205 and no hotter.  Looking for 225 to 230.


So, did the inlet mod, put a deflector/tuning plates in (still working with them for placement etc) and ended up putting the exhaust grate extension back on in hopes of getting the temp to even.  Last burn charcoal to start with oak from then on.  After a long while I was finally able to get the exhaust end to be 225-230 at the grate, but the firebox side (used two grate probes) was 275-280 while doing this.  Seemed to use a lot of fuel to finally get the result.   Then did not hold extremely long and needed more wood.


Going to keep trying.


Thanks again for the post.

post #6 of 46
Yes it has that inlet vent I would get rid of the basket. I had one and it did not work well. The fire need to breathe. Use charcoal to start your fire then go to all wood. You can use a handful of charcoal when adding splits if they get low. But I had much better luck and a hotter fire without the basket, without trying to burn all charcoal This pit is designed to burn wood.
post #7 of 46
Also don’t rely on the temp gauge. Get one that you can put on the cooking grate.
post #8 of 46
And I always tend the fire by opening the lid, not the side door. Once its off a running that door never gets opened.
post #9 of 46
Thread Starter 



That is interesting about the basket! 


Last burn was a chimney of charcoal and then just oak from then on.  Just seemed to use a lot of wood trying to get everything hot enough and stay hot.  Still learning and figuring out the smoker so maybe don't have a concept on that.  I have cooked a rack of ribs (exhaust end) on it and a brisket at the same time (firebox end).  Cooked the ribs all the way on it, but got frustrated with the temps not staying up (was not yo-yoing the vents around, just making small adjustments and adding fuel) and pulled the brisket after 4 hours, wrapped it and put it in the oven to cook the rest of the way.  Moved the ribs to the firebox end to finish them out as the exhaust end was too low.  Both ended up being very good.  As I said, still trying to learn how to work this smoker correctly.  Not cooked anything in about two weeks now though so having withdrawals.  Nothing on a good sale in the ads.


Yes, that gauge is pretty useless.  I contacted the company to see if it was adjustable, but the person I got was less than helpful and could not answer my question.  Thought it would be of use if I could calibrate it to be approx. the exhaust end grate temp.  I've been using digital temp probes stuck through the end of a potato on each end of the smoker to get grate temps.  I'd like to get some good gauges and mount them lower in the door to see if I could get some accuracy.  Just can't afford it at the moment. 


The other thing I wondered about was the drain tube.  I have seen smoke come out of the tube at the bottom while doing a general burn on the smoker.  I wondered if this should be at least plugged?  There are no threads on mine for a cap or ball valve so last burn I stuck a piece of wadded up tin foil in it.  Don't know if it did anything, but with all the thing about sealing up the doors and stopping the leaks this seems like a pretty big one. 


Thanks again for the posts!  I'll try the basketless deal and see if I have better luck.  Now just need to find a good brisket or spares on sale............

post #10 of 46
One thing I have found is be patient and let the pit warm up good and stabilize. From the time I light it until I put food on it might take 2 hours.
I have ¼’ tuning plates so that may be why it works better for me if I wait until everything heats up real good.
Then the temps don’t bounce around as much. When the temp starts to fade about 10 degrees I just add another preheated (important) stick (not too big, important too, maybe the diameter of a tennis ball ) it takes about 45 mins before adding another one. This is with hickory, type of wood makes a difference too
post #11 of 46
Thread Starter 

Thanks for that info!  Very useful!


How much do you usually put in (charcoal and or wood) to get things warmed up?


I watched Lang's video and so have the top door open, the cook chamber open and the exhaust full open.  I did one chimney of charcoal and three oak logs about fist diameter and probably 15 inches long to start.  I let them burn pretty good with all open to burn the bark they had on them.  Then I closed the cook chamber and left the firebox top door open and side door open.  This drafted some through the cook chamber.  The wood was not coals at this point is why I left the doors open.  Once the wood was most of the way coals and glowing I put a couple of pieces of oak on that was probably 3x5 on the end and 8 inches long.  I let that light pretty well and get a good burn going, but it was still wood, if that makes sense, when I closed the firebox top door.  I kept the firebox side door open and from that point was trying to heat up the cook chamber good. 


I probably did not leave it long enough and I did not really keep up with exactly how long I waited, but it seemed a long while.  Temp on exhaust end was still too low.  Tried the Lang deal of propping the door slightly open to draft in more.  Made a little difference, but not much.  Ended up stirring the wood and coals around and adding another piece of oak about the same size.  Not sure how long to wait for the new piece of wood to burn or how far it should burn before closing the lid.  Oh, and beyond the initial three pieces to start the fire, all the rest of the wood I have taken the bark off.


Anyway, that is what I did.


I really appreciate the tips etc. and your taking the time to post.


On the 1/4" tuning plates, I've been thinking something like that might help.  My tuning plates are just the home depot 16g, I believe, 18 x 6 sheets.  I have them propped in except for the first ones.  Those I bent the first plate and bolted it in using the existing bolts.  Tried to get the opening closer to the calculator opening requirement.  The next plate is angled off of that with a couple of tack welds holding it together and then the next is right off of that one and tack welded on to the previous plate.  Was trying to force the heated air further into the chamber before it had a chance to rise.


Funnily, may have been just a fluke and just happened to get to that temp as it took so long, but I got my best temp exhaust end by putting another plate on the exhaust end with a 1" gap from the end of the chamber.  Another 1/2" gap from it and then a third another 1/2 gap from it.  Seems strange, but guess they added mass and the hope was that they would catch some of the heat/air turbulence at the end of the grill and delay it there making that end hotter.  As I said, who knows if it was a true deal.  Waiting on the next cook to see if it repeats as I don't want to keep wasting fuel just doing empty burns.


Anyway, been wondering about adding mass that would retain heat.  I don't have ready access to 1/4 plate so been wondering about maybe some sort of brick or ceramic type deal that would retain heat.  Something to look into.

post #12 of 46

Not sure what to tell you here ''not much help'' I also have the OKJLH and since I raised my firebox grate about 4'' added a charcoal basket I don't have any problem getting my smoker up past 275-300 . before adding my truning plate my temps in the CC would vary 50-60 deg from end to end the turning plate has them pretty close within 10 deg.. Not sure about the 2 hours to get temps 225 since that's what I do 90% of my smoking at,  mine reaches that in less than 30 min. I also added the down pipe for exhaust

post #13 of 46
Im not saying it takes 2 hours to get to cooking temp. I am saying I like to let it go and warm up and stabilize before putting wood on and usually let it sit about 2 hours before doing that. I am I could put it on before that. And that is with wood.
I usually cook between 275-300
post #14 of 46
My OKJLH takes a long time to warm up but once there it holds 225-250 easily. My tuning plates are gapless from FB to a little over half way across CC then have another plate with small gap and my pit temps hold less then 5 degrees difference from side to side. I tried putting small gaps all across but FB side ran way to hot.
post #15 of 46
I also decreased the size of my FB to CC opening and changed exhaust to be all the same size as the pipe welded in the CC. I do feel the inlet is to small so I run it with door open until temp comes up then shut door and adjust accordingly. I did trim inlet opening so it would be as big as it can be
post #16 of 46
Thread Starter 
Originally Posted by james1nc View Post

Not sure what to tell you here ''not much help'' I also have the OKJLH and since I raised my firebox grate about 4'' added a charcoal basket I don't have any problem getting my smoker up past 275-300 . before adding my truning plate my temps in the CC would vary 50-60 deg from end to end the turning plate has them pretty close within 10 deg.. Not sure about the 2 hours to get temps 225 since that's what I do 90% of my smoking at,  mine reaches that in less than 30 min. I also added the down pipe for exhaust

Thanks for the post.


I raised my firebox grate using the supplied grates I just put them cross ways to get more height like ButtBurner did.  Seems to help.  I go in and use a piece of rebar through the inlet to move the ash around and stop ash build up (my OJLH does not have the ash drawer I've seen on some smokers that look similar).  I've been thinking about seeing what I could come up with to raise the grate just a bit higher to help flow as the cook goes on.  Maybe some bolts through the grates to raise it up or perhaps get a small piece of angle and weld some legs on.  Don't want to go too high though as want air under, but also around the sides etc. to keep things going.


Your post adds support to my thought I need to work on the tuning plates.  I've seen the same 50 degree variance or so.  How thick are your tuning plates?

I have the thought that mine are just too thin to be doing an adequate job of radiant heating to even things out and they are just working with flowing heat as it where.

post #17 of 46
Thread Starter 

Wow ButtBurner!  I'd be happy with a consistent 225-230:439:

post #18 of 46
Thread Starter 
Originally Posted by Dockman View Post

My OKJLH takes a long time to warm up but once there it holds 225-250 easily. My tuning plates are gapless from FB to a little over half way across CC then have another plate with small gap and my pit temps hold less then 5 degrees difference from side to side. I tried putting small gaps all across but FB side ran way to hot.

Great pic!  What thickness of metal are you using?  I was only able to get the little sheets from Home Depot that I think were 16g.   Worth at least my trying to space them like yours though.  My plate from the opening onward looks pretty much the same as yours.  What I did was bend the first 18x6 piece to get an angle and then removed the top four bolts holding the cook chamber and firebox together.  My plate attaches using the four bolts, but the bottom two are right at the angled bend.  From there it goes solid on.  Just measured it and the plate extends solid from the side of the cook chamber only 13 inches out.  I'll see if I can post pictures of everything I have so far.


If you don't mind my asking, how far do your plates extend from the side into the chamber solid?  Also, what is your gap from the solid plate to the single plate?  Width of the single plate?


I guess while I'm being nosy, how did you do the exhaust pipe and where did you find it?  I've not been able to find the tubing the right size and material.  I tried the home stores and auto part places, but no luck.  Right now I have a piece of aluminum dryer duct in place, but that isn't ideal.


I kick myself because I ordered a cover from the manufacturer and considered ordering another exhaust pipe and sharing ship.  Was just too cheap and did not want to spend the $35 or whatever it was for the pipe.  Of course now to order it would be the $35 plus the full whack on ship!

post #19 of 46
Thread Starter 

Don't know if you can see it with the sun etc., but here is the plate on the firebox end. 


This is on the other side.  1" off the exhaust side wall and then the other two plates are 1/2" apart.  I'd still like to get it closer in temp as this set up is still to wide a range from side to side.  You can also see my cheesy dryer vent in the pic


Just for grins, here is the inlet mod.  The painted/welded round nub you see at the bottom left is actually my first attempt welded back up and not the original adjuster arm attachment.  My first attempt I flipped the plate and thought I'd put the adjuster bolt at the bottom.  Well, not only did my effort scrape the bottom of the arc as it moved, but it also did not give me very much increase in inlet size.  Then it dawned on me to move the adjuster up to the top area.  More movement the way the damper plate arcs and gives more inlet volume. 


 Here it is most of the way open.  It holds pretty well as I added a spring and washer to the nut on the back of the pivot, but I need to tighten it a smidge more.  Either way, much more inlet volume.  Only down side is that now the damper will pivot so far that the side door will not open if you have the inlet adjusted all the way open.  Not an issue for me as I'm loading the firebox from the top lid.  If I do need to open that door, simple enough to close the vent from full open to about half way open and the door works no problem as the damper is out of the way.

post #20 of 46
May plates are 26" over from CC then a 2-1/2" gap to last plate which is 4" wide! My plates are 17" long.
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