Side Burner Air Intake "Butterfly" Modification?

[ski-freak]

I am thinking about closing off the upper of the two air intake butterfly openings on my Oklahoma Joe Longhorn Smoker/Grill to improve its airflow pattern and possibly efficiency. Has anyone done this already and can provide me with their insight, or does anyone have any thoughts on this. Here is what my OK Joe looks like:

temp gauges.JPG

• ski-freak
• Oct 23, 2012

Here is the view from the outside of the butterfly air intake (2 openings  that can be adjusted from wide open as shown here, to fully closed, and in between):

Butterfly.JPG

• ski-freak
• Oct 23, 2012

Here is where the placement of the two butterfly openings are relative to my Charcoal Basket, which sits directly atop the original OK Joe Charcoal Grate, and immediately under the original OK Joe Direct Searing Food Grate (there is an Ash Drawer underneath which is a very convenient feature):

OK Joe Basket Side View.JPG

• ski-freak
• Oct 23, 2012

I am considering removing the movable butterfly plate visible above and welding a piece of sheet metal across its upper opening, and then re-installing it so that I would only have an adjustable lower butterfly opening. I am thinking of doing this because at times I have seen smoke coming out of the upper opening, and the upper opening seems to be poorly placed relative to the fuel load. I use this Smoker/Grill for Smoking in the Indirect Heated Food Chamber, as well as for Direct-Sear Grilling on the Food Grate in the Side-Burner Firebox (see the placement of this Food Grate above). Can anyone point out any Pros/Cons to the upper butterfly opening before I make this modification?

Thanks in advance for any guidance!

 

[daveomak]

Chris, evening.... Upper and lower air intakes in a firebox can be an advantage... Too bad the manufacturer did not make them independent...  

If I were to remodel the intakes, separate controls would be in order....  Dave

 

[ski-freak]

Good Evening Dave! That's indeed a very interesting concept. My initial thought to accomplish this would be to cut a piece of sheet metal into a triangle with a small tab extending on one of its sides. Then I would drill a hole at the point of the triangle and stack it on the same pivot bolt as the original moving damper. The tab would be bent at 90 degrees to the rest of the triangle's surface, and stick out of the upper hole so it could be accessed from outside - and then it could be slid back and forth to separately regulate the upper hole. That would be pretty easy to fabricate, and would be less permanent than welding. Certainly it's a good place to start!

Do you think that the existing upper hole is in the best, or at least a reasonably good place to be of value as an upper air intake? If not, I could eventually continue along the line of sealing the existing upper hole on the existing movable baffle, and then create a whole new upper air intake in a better position - though that's a little bit more involved mechanically. Plus, I really don't know where it should optimally go.

So you have a better feel for the firebox's exhaust port, here is the view into the side door showing the position of the firebox opening to the indirect heat cooking chamber:

Basket 3.JPG

• ski-freak
• Oct 23, 2012

The firebox opening today is somewhat blocked because I made and installed a drop-in convection/diffuser plate to spread the heat from the hot-spot up against the firebox across the indirect heat chamber (that worked quite well):

Convection Plate 2.JPG

• ski-freak
• Oct 23, 2012

 

[daveomak]

Chris, The concept behind dual intakes..... lower air to control the heat, upper air to control the air flow through the smoker to add something similar to a convection oven....  It would just increase your control over cooking is all... That concept and control would take some time adjusting to, but might be worth it.... Other smoker builders use that concept....  It might take time figuring out a design for the damper configuration and several tries at it... the end result could be awesome.....  

I really like the diffusser and basket... those should work very well....  The opening, to the cooking chamber, looks like it is blocked in the picture....  right behind the basket it looks blocked...  maybe the basket is obstructing something I can't see....  

 Dave

 

[ski-freak]

Thanks Dave!

The top of the charcoal basket is immediately below the opening between the two chambers (the two chambers are bolted together), so what you see directly behind the basket and partially obscured by the basket is the wall of the firebox below the hole. What you see through the hole is the wall at the other end of the cooking chamber - which is 40" long, and this I think is limitation to the depth as presented by my iPhone's camera since it looks only a couple inches deep and certainly not 40 inches.

Thanks again for the idea though and I will report back with progress...

 

[ski-freak]

OK, instead of permanently closing off the upper air intake I made a little valve out of a piece of 16 Gauge sheet metal, with a bent tab for a control handle:

Valve1.JPG

• ski-freak
• Oct 25, 2012

Here's how it went in (Upper Air Intake Valve Wide Open):

Valve2.JPG

• ski-freak
• Oct 25, 2012

Upper Air Intake Valve Half Open:

Valve3.JPG

• ski-freak
• Oct 25, 2012

Upper Air Intake Valve Closed:

Valve4.JPG

• ski-freak
• Oct 25, 2012

 

[ski-freak]

The normal adjustability of the Oklahoma Joe Longhorn Air Intake still allows full control over the Lower Air Intake, and here it is shown closed:

Valve5.JPG

• ski-freak
• Oct 25, 2012

Not too bad for a simple inexpensive and easy (and fully reversible) modification to the air intake scheme - and no welding needed as the bent tab allows better adjustment range since it's so thin...

 

[daveomak]

Chris,..... Freakin' genius.... I love it....  Killed 2 birds with one rock.....  I think you will love the control you have over the fire, smoke and temp..... It don't get no better than that.....   Dave

 

[ski-freak]

Dave, this valve plate only came about because of your encouragement to consider a way to preserve the upper air intake, and to also incorporate independent adjustability of the two original openings, so THANK YOU for helping me to better understand air intake principles before I implemented a solution.

The mechanical part is easy! I made the valve plate with only simple hand tools out of box store sheet metal, so anyone with an Oklahoma Joe Longhorn or other smoker/grill with this type of butterfly air intake could make one themselves - for their own air intake mod. 

 

[daveomak]

Chris, thanks..... now, if you would, document the results for others to learn from.... That would be cool.....  Dave

 

[ski-freak]

I will report my findings after some time experimenting with this new feature.

 

[ski-freak]

Experimented a bit while smoking some Cornish Game Hens and Turkey Breast, and glad I didn't close off the upper opening altogether. The best heat and smoke flow seemed to be with the bottom intake wide open, and the top intake half open. It was also cold and dark out (just under 50F) so I was pushing for heat. The upcoming time change Tomorrow night gets it even darker, and as November progresses even colder...

 

[ski-freak]

Now that it's cold out I need to use more charcoal to maintain the same temperature, but wide open on the bottom intake, half open on the top intake, and wide open on the exhaust stack is still consistently the best configuration. My charcoal basket will hold 2 Weber chimneys of Stubbs briquettes, plus lump charcoal, and wood chunks and sticks.

 

[daveomak]

Chris.... That is great info for folks wanting a great mod for their SFB smokers...   It is good to know how well it works....   

 ...

 

[last cast]

Just a thought.. Instead of chunks would it make sense to use a single larger stick like a small log to keep the heat up 

 

[tcoop4899]

Coming in a little late on this one but here goes. Ideally you want your intake to be below or at the very least even with your fire great. This allows for optimal draw by pulling the air in below your fire drawing thru the fire into the cooking chamber and out your exhaust. If possible i would make two seperate butterfly controls for the top and bottom holes with the butterfly openings being as large as the cut outs in the door. Right now when you have the butterflies wide open you are only using 1/3 to 1/2 of the actual cut out size opening. My guesse is that if you open the bottom hole to its full size you wont need the top hole at all. In one of your pics it looks as if the top hole is almost even with your opening into your cooking chamber. If conditions were right and the wind was blowing in the right direction that could possibly explain why at times you see smoke coming back out the top hole. It is basically causing a backdraft.

 

[ski-freak]

Tcoop: See the 3rd picture in the Original Post. The lower hole is indeed below the charcoal basket (bed of coals). The upper hole is just below the top of the charcoal basket, so its position relative to the bed of coals depends on the depth of the bed of coals. In the case of a shallow bed of coals the upper hole is positioned above the bed of coals, and some smoke can/will exit the upper hole naturally. Maybe you're right that making the lower hole bigger could be beneficial, but note that only the right edge of the existing movable butterfly plate could be opened up, if you want to still be able to completely close the lower opening. This would also not be easily reversible once cut, as the only way back is to fabricate a new movable butterfly. In any case, I'm happy with the way my Oklahoma Joe Longhorn is currently working.

 

[daveomak]

Coming in a little late on this one but here goes. Ideally you want your intake to be below or at the very least even with your fire great. This allows for optimal draw by pulling the air in below your fire drawing thru the fire into the cooking chamber and out your exhaust. If possible i would make two seperate butterfly controls for the top and bottom holes with the butterfly openings being as large as the cut outs in the door. Right now when you have the butterflies wide open you are only using 1/3 to 1/2 of the actual cut out size opening. My guess is that if you open the bottom hole to its full size you wont need the top hole at all.  In one of your pics it looks as if the top hole is almost even with your opening into your cooking chamber. If conditions were right and the wind was blowing in the right direction that could possibly explain why at times you see smoke coming back out the top hole. It is basically causing a backdraft.

Coop, morning.....  Some folks have noticed the firebox gets extremely hot and the cook chamber does not come up to temp.... To alleviate that situation, adding extra air above the fire, moves that extra heat to the cook chamber resulting in better cooking temps and the reduction of wood being used in the cooking process.. more efficient use of wood....   This modification has been proved beneficial to many folks with SFB smokers...   Several members have done this mod and are very happy with it....  Theory does not always work where physics is involved....  Poor smoker design from the factory makes necessity the mother of invention....  In this case, a great invention...  

Dave

 

[ski-freak]

I made a small refinement so that the thickness of the valve tab will no longer block the butterfly from closing all of the way. I simply used a flat file for a minute or so to make a small notch:

Butterfly 1.JPG

• ski-freak
• Apr 21, 2013

 Now the Butterfly Air Intake can be closed all of the way:

Butterfly 2.JPG

• ski-freak
• Apr 21, 2013

 

[daveomak]

And I suppose you were sitting in a  lawn chair just starring at the firebox for hours thinking...... what can I do to improve it now....   Been there....    and by golly it looks perfect.....   Good job......    Dave