Firebox damper question.

[DaveNH]

I built my smoker with a chargriller firebox. The SFB really isn't all that air tight, so temps have a tendency to creep up if I put too much charcoal in the basket. If I run at 240~250 I can only add a half load (little more than 1 chimney) of charcoal using the minion method, inlet damper closed. I get maybe 3 hrs at this temp. I can go longer if i turn on the element and controller, but I'd like to get more time out of the charcoal.

I'd like to be able to load the basket, still keep the temp down and get a longer burn time. Would it make sense to add a damper (maybe a throttle plate) to the SFB outlet to throttle it down some? Hoping to slow the burn down and maintain temps longer with more fuel.

Here's a few pics from the build of the firebox and opening.











Greatly appreciate any ideas or suggestions :).

[Texas-Hunter]

I have the same firebox on Project X and have the same problems... I made a small charcoal basket and keep it at the intake end of the firebox.. It really has helped but I do still get temp peaks and falls... Im just toying with it till I get her dialed in...

[DaveNH]

I have the same firebox on Project X and have the same problems... I made a small charcoal basket and keep it at the intake end of the firebox.. It really has helped but I do still get temp peaks and falls... Im just toying with it till I get her dialed in...

Ken..I remember project X now, how's she doing :). How long do you go on a basket full and what size vent did you use? Wonder if I made my vent pipe too big. Just under 5" pipe.

I insulated a couple inches all around. So it doesn't take much to heat it up. I know closing down the vent isn't the thing to do, don't want to trap the smoke. But I can partially close the vent and it does cut the temp/airflow back. So thinking make the firebox outlet adjustable so no trapped smoke.

[Texas-Hunter]

I running a 3" vent on mine.. Thats about the same size as the intake.. And since the basket I am using is a 12x12x8 my run times are around 2 to 2.5 hours before I add any lump...

[Fireguy]

in theory your idea makes since to me. I added one to my sfb to experiment with air flow and longer burn. I am still experimenting though. I does seem to help, but not as much as I had hoped for.
In conjunction with my Coal basket.. I have the top Damper opened partially and the bottom one cracked open. It does seem to slow the burn time down and maintain a lowert temp for longer. But like I said still playing with it. heck give it a shot and see what you come up with. good luck

[Capt Dan]

personally from the folks I know who have sfb with lump, 3 hrs is pretty good time. I doubt you could improve it by shutting down the exhaust into the smoke chamber, you may risk getting a smoke you don't want. I would work with the intakes. I am thinking the only way your gonna better the burn time is whith a stoker, or UDS smoker.
The other thing it the smoke chamber is pretty good size, you can put alot of meat in there, and to smoke that much meat with a 3 hr burn is darned economical if you ask me.

[HawgHeaven]

personally from the folks I know who have sfb with lump, 3 hrs is pretty good time. I doubt you could improve it by shutting down the exhaust into the smoke chamber, you may risk getting a smoke you don't want. I would work with the intakes. I am thinking the only way your gonna better the burn time is whith a stoker, or UDS smoker.
The other thing it the smoke chamber is pretty good size, you can put alot of meat in there, and to smoke that much meat with a 3 hr burn is darned economical if you ask me.

Yeah, a 3 hour burn is really good! I'd be happy with that for sure!

[DaveNH]

Thanks guys...

Maybe I'm expecting too much. No other charcoal unit to compare against and I can never seem to leave well enough alone :).

This rig doesn't need a lot of BTU's and pretty much have to run it with the SFB intake closed to keep the temp down.

Would reducing the firebox opening be worth a shot? The SFB was designed to be on an uninsulated smoker, thinking a little recalibration might do the trick.

[Fireguy]

like the others said, 3 hrs is darn good. with my mod ive stretched my time to 2-3 hrs on 2 chimneys, vs. 1+. I doubt restricting the void between the chamber and the sfb would do you any favors. I would concentrate more on the intake also. Maybe try more Lump, less intake, with minion.

[DaveNH]

like the others said, 3 hrs is darn good. with my mod ive stretched my time to 2-3 hrs on 2 chimneys, vs. 1+. I doubt restricting the void between the chamber and the sfb would do you any favors. I would concentrate more on the intake also. Maybe try more Lump, less intake, with minion.

I hear ya. I'll leave it alone :).

[Capt Dan]

Never hurts to explore your horizons dave. Keep looking at it, you may stumble upon something, never know.I do think you are at the top of the curve, and lil things you do or tweek may get ya another 15-30 minutes. I would say that the most important thing is to get the product that you desire.While its not a rocket science, some things we do to make it easier, may also sacrifice some flavor or tenderness. Its all in the learning, and it sounds( and looks) like ya got a pretty good handle on it so far.

I would love to see that thing loaded and chugging along with TBS.

[DaveNH]

Well...got around to adding a seal to the clam shell cover on the firebox and what a difference in temp control. I did a dry run with two chimneys of RO lump and the air control was awesome. Finally working like it was supposed too. I could adjust the air intake for 225 and it was nice and steady for 4hrs. Next test is with some briquettes.

This works really well slowing down the burn. I'm not sure if an uninsulated chamber will get the same burn time (may need to give more air for a hotter fire) but the temps will be way more stable with the air only coming through the intake at the back of the basket.


Pre-drilled 4 holes in each edge of the opening, laid down a bead of high temp gasket adhesive (came with the gasket). Then used stainless rivets to secure the gasket into the adhesive and onto the box. Worked the head of the rivet through the braid and the shoulder of the rivet held the gasket nicely when attached. You also have to drill and rivet the ends of the gasket where they meet.











Had to tweak the cover a little to get some clearance for the gasket. Did that with a 1/4" rod near the hinge and closed the cover giving it a slight bend.







Last but not least a little bungy action to keep it closed tight.




The gasket looks pretty solid and should hold up. With a good seal on the firebox it can now be loaded without everything catching and driving the temps up.

[jbchoice1]

I was with ya on that one... great to see you getting every little bit outta that thing... and I bout fell outta my chair when I seen the bungy... classic...