trouble with okj...tuning plates or horizon plate?

daveomak said:

It's resting against the FB... The deal is, you are trying to seal the FB/CC so all the smoke/heat travels under the plates... or something close... then the gaps distribute the heat to the cooking grates....
In the picture, the plates could have been narrower... that would have allowed for more slots to move heat upward to the cooking grates.. a more uniform cooking surface... "MAYBE".... those might work perfect.... just saying there are options...

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Ya I was thinking those plates were a little large. Love the idea of the plates to move around for your needs on a certain cook.
Is it necessary to have the "baffle" section welded together, or would it suffice to have two different plates just leaning in that manner?

Not necessary to weld... Get them to stay any way you can..

Try changing your stock 3" smoke stack to 4" to improve the draw. It is cheap & easy to do since the output is already 3.5". I think the tuning plates and the CC elbow above the grate restrict air flow too much. When i removed one of my plates it helped, but when combined with a 4" stack the pit works 95% better. I burn sticks and leave the firebox door open.

Heart of Dixie said:

Try changing your stock 3" smoke stack to 4" to improve the draw. It is cheap & easy to do since the output is already 3.5". I think the tuning plates and the CC elbow above the grate restrict air flow too much. When i removed one of my plates it helped, but when combined with a 4" stack the pit works 95% better. I burn sticks and leave the firebox door open.

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Ya I will not have the elbow above the grate with tuning plates. One sort of seems to negate the other.

What size are your plates? 6x16? I think I have read some people doing 8x18, but I feel like that places them to high and close to the grate.

My tuning plates are 3/16" thick, 4" x 18" and sit 3" below grate level. The CC is 20” in diameter x 40" long. I use 2 tuning plates plus the firebox diffuser. The diffuser is mounted against the firebox with spacers creating a 1" air gap between it and the firebox bulkhead. The first 4 x 18 plate butts up to the diffuser, then a 1/2" or so gap, followed by plate # 2. I had 3 plates in but they kept too much heat at the firebox end. I found in my OKJ that when the elbow was removed the temperature on the end dropped too much. I think it was because by my plates only go half way across the CC the 4" stack drew everything out towards the high exhaust thus cooling the last 10" or so, at least that is what the Igrill 2 probes showed was happening. With the elbow installed the temps remain pretty consistent all the way across. The above set up produces a temp differential from end to end of a few degrees to about 10 and a 30 degree increase from the grate level to the top of the CC. This set up took about a year or more of experimenting to finalize but hey, every man needs a hobby. Sorry for rambling on. I hope this makes sense.

Heart of Dixie said:

My tuning plates are 3/16" thick, 4" x 18" and sit 3" below grate level. The CC is 20” in diameter x 40" long. I use 2 tuning plates plus the firebox diffuser. The diffuser is mounted against the firebox with spacers creating a 1" air gap between it and the firebox bulkhead. The first 4 x 18 plate butts up to the diffuser, then a 1/2" or so gap, followed by plate # 2. I had 3 plates in but they kept too much heat at the firebox end. I found in my OKJ that when the elbow was removed the temperature on the end dropped too much. I think it was because by my plates only go half way across the CC the 4" stack drew everything out towards the high exhaust thus cooling the last 10" or so, at least that is what the Igrill 2 probes showed was happening. With the elbow installed the temps remain pretty consistent all the way across. The above set up produces a temp differential from end to end of a few degrees to about 10 and a 30 degree increase from the grate level to the top of the CC. This set up took about a year or more of experimenting to finalize but hey, every man needs a hobby. Sorry for rambling on. I hope this makes sense.

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Wow. A lot of great info here. Thank you for that.

That mounting of the diffuser is very interesting. Do you find that the gap gives problems with the differential?

I'm thinking that the stock stack on the OKJ and the elbow would not be useful together. Maybe next time you are smoking could you snap a quick pick of the plates and diffuser? You have been very helpful so far, and I may be over staying my welcome so to speak haha.

Nothing wrong with having a hobby. I bet all of that tinkering makes the family and friends a happy and full bunch.

Thanks again.

Blowing Smoke - Here is a picture with the grates removed. The plates stop almost dead center of the 40" CC. There is not a gap between the diffuser and the first plate, it just looks like it in the picture. When first setting this up there was too much downward angle on the diffuser and therefore it blocked flow. I kept bending and checking but no matter how much I decreased it the FB end remained at least 50 degrees hotter, even after it was almost on a 90 degree angle and was not below the opening between the FB & the CC . So out of frustration I added the spacers you see to the far right and immediately the the two ends of the CC became within 10 to 20 degrees of each other. I used the pit like that for a time but noticed there was a draw issue, especially on higher humidity days. I always check the weather prior to firing up and turn the firebox facing into the wind. To cure the draw issue I increased the stack to 4" and llke i said in an earlier post there is now but a few degrees difference now from the FB to the end of the CC. I always kept a log and used 3 IGrill2 probes when making changes to the plates and diffuser.

Heart of Dixie said:

Blowing Smoke - Here is a picture with the grates removed. The plates stop almost dead center of the 40" CC. There is not a gap between the diffuser and the first plate, it just looks like it in the picture. When first setting this up there was too much downward angle on the diffuser and therefore it blocked flow. I kept bending and checking but no matter how much I decreased it the FB end remained at least 50 degrees hotter, even after it was almost on a 90 degree angle and was not below the opening between the FB & the CC . So out of frustration I added the spacers you see to the far right and immediately the the two ends of the CC became within 10 to 20 degrees of each other. I used the pit like that for a time but noticed there was a draw issue, especially on higher humidity days. I always check the weather prior to firing up and turn the firebox facing into the wind. To cure the draw issue I increased the stack to 4" and llke i said in an earlier post there is now but a few degrees difference now from the FB to the end of the CC. I always kept a log and used 3 IGrill2 probes when making changes to the plates and diffuser.


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I see. Originally I was expecting the see plates all the way across. Very interesting set up. That is good to know about the diffuser side as well. Something to consider. I wonder if 6" plates would make a difference. I think I will go with 6" and cut down from there if necessary. Thank you for grabbing that pic. Also, do you have thermometers in the hood? If so how many, and the location?

bl0wingsm0ke said:

I see. Originally I was expecting the see plates all the way across. Very interesting set up. That is good to know about the diffuser side as well. Something to consider. I wonder if 6" plates would make a difference. I think I will go with 6" and cut down from there if necessary. Thank you for grabbing that pic. Also, do you have thermometers in the hood? If so how many, and the location?

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6" plates should be fine. I have one thermometer in the top and it is almost to the top on the left side. You can see it's probe just above the left hinge. I still use is the one that came with the unit originally for it is accurate enough (within +<10 degrees of my IGrill2 probes) for what i use it for. If it ever dies I will replace it with a Tel-Tru. See the little tube sticking out of the far left end below the elbow? I feed my temperature probe wires through it.

Heart of Dixie said:

6" plates should be fine. I have one thermometer in the top and it is almost to the top on the left side. You can see it's probe just above the left hinge. I still use is the one that came with the unit originally for it is accurate enough (within +<10 degrees of my IGrill2 probes) for what i use it for. If it ever dies I will replace it with a Tel-Tru. See the little tube sticking out of the far left end below the elbow? I feed my temperature probe wires through it.

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O that's a great idea rather than having any gap on with the lid.