# The Mud Pit II is born: 275 gallon reverse flow build

SMF is reader-supported. When you buy through links on our site, we may earn an affiliate commission.

#### jmud

##### Meat Mopper
Original poster
Layed off carpenter, figured I'd take a month and put the pieces together. Not sure if it's 250 or 275 gallon, but here's what I got:

38 by 60 tank
68012 cook chamber
Firebox recommended 22670
Firebox 32 by 27 by 27
Dual 4 inch smoke stack: 94 inches total
Three 5 inch square air inlets
Firebox to cooker opening of 188 sq inches
Segment height 8.5 inches
AB cord length 31.7 inches

What ya all think???

I come up with a stack about 7" dia. about 30" + in length (minimum).... If you used 2 stacks thinking that would double the volume to equal 1 larger stack... 2 each 4" stacks is equal to 1 each 6" stack... It take 4 each 4" stacks to equal 1 each 8" stack.... also, using 2 smaller stacks, you have increased the surface area and friction loss.... not good in a smoker... friction will kill the air flow... Dave

4" dia. = 12.6" circ. .................................... 12.6 sq in
8" dia. = 25.1" circ. and 4 times the area.... 50.2 sq in

Last edited:
Ok, makes sense. I just wanted a dual stack for aesthetic reasons, look cool like a semi. What height should each be if they were 4" or 6"?

Last edited:
Wow, never did the math on that to realize the difference, thanks Dave.

Ok, makes sense. I just wanted a dual stack for aesthetic reasons, look cool like a semi. What height should each be if they were 4" or 6"?

If you want a smoker that looks like a semi..... You will need 2 each 6" stacks 30" above the top of the cook chamber....

6" dia x 2 = 38" surface area per inch of height

8" dia = 25" surface area per inch of height

surface area to volume is something that needs to be considered when looking at stack efficiency......,

Last edited:
Or am I better off just using a single pipe

I also looked for a propane tank. Hard to come by. Tried fuel places, junk yards, craigslist and came up short. Firebox certainly will be 1/4 inch. Cooking chamber will be 1/8

Just visit a junkyard and tell the attandant that you will give them a finders fee if they call you when one shows up. Then you will have to also pay scrap steel price for the weight of the tank.

The only scrapyard in our area, let's just say he loves money. I did this run around with him once before for the 100 gallon tank. Didn't really feel like spending 500 for the 100 gallon then, god knows what he would charge for the larger one. I've seen oil tank builds on here and think people were happy with them, so I'll just stick with it I guess

Check with the propane companies they swap out and exchange out dated tanks all the time, usually sell them at a pretty decent price, at least around here they do.

Gary

I also looked for a propane tank. Hard to come by. Tried fuel places, junk yards, craigslist and came up short. Firebox certainly will be 1/4 inch. Cooking chamber will be 1/8

Yea I already tried, no success

On a 250 gal tank a 4" or several 4" just won't look right, I would go with a min. of 6",  That will give your smoker a clean look and will flow better.

Gary

i agree with Gary on the stack.

as far as a tank, dont give up, and dont settle for anything other than what you want and in good condition. You will find it if you stay at it. Its one of those things you have to keep your eye out and drive different routes than you usually drive until you come across it.

and always have cash in your pocket so that your ready!

Alright two 38-40 inch stacks it is

I'm kinda under the gun here to get it built. I'm layed off for probably only a month and so I got a month to build it. I know I can do it. I have a pretty big cooking gig for our fire dept gun raffle. 240 lbs. that's a lot for my first pit. I got the oil tank now, the tee nee boat trailer for it, so I'm goin for it. If I had the propane tank I'd be in a different route for a trailer, don't think it would hold up to twice the weight. So if all is in place for it in in for it. I'm sure it will be a great build

Nothing wrong with that, build you a quicky and get some experience! You can always sell it down the road and build another!

Nothing wrong with that, build you a quicky and get some experience! You can always sell it down the road and build another!

Nothing wrong with that, build you a quicky and get some experience! You can always sell it down the road and build another!

Heck the first one I built I got guys wanting to but it for 2 grand. I just can't do it. The third one will be one that I take my time getting pieces together and going all out short of putting spinners on the wheels lol

Here is the tank. Sawzall to keep the sparks down so I don't explode

SmokingMeatForums.com is reader supported and as an Amazon Associate, we may earn commissions from qualifying purchases.