Ongoing long burn tests

helljack6 · Aug 7, 2009

Well, I didn't have a lot of success with regular charcoal over the past couple of days so I changed gears and tried lump. Fired the UDS at 530pm last night and brought it up to 240ish around 615pm and started the clock from there. From 615pm through 1130pm the temps did nothing from slowly drop regardless of what I did. Here are the pictures of the lump this morning after I pulled it out of the UDS.

As you can see I didn't use a great deal fuelwise, but the lump basically burned straight down and didn't ignite any of the surrounding fuel. This was fired in #5 which is a DOT approved 55gal drum, three 3/4 intakes of which two are capped and one has a magnet over the opening. I had set the magnet at half and capped the other two when the temp hit around 220 and the basket which consists of expanded mental formed to a weber 18" charcoal grate sits 4 inches off the bottom. Bear in mind I was in fact able to hold temp for about the first hour and after that is when it did nothing but fall.

CONCLUSION: Cowboy lump ISN'T a quality fuel for use in UDS style cookers, however, let it also be known that as far as lump goes, Cowboy lump does live up to the expectation and produces very little ash as shown in the second picture. I will continue to run tests this weekend with Kingsford Comp and RO lump and post those results as well.

hog warden · Aug 7, 2009

One hole, half blocked by a magnet, probably left it starved for air. I use the ball valve setup, wide open. If I close that down much, I too lose temps and it goes out. Play around with the size of your opening, but start out hot and work down from there. I smoked a brisket this week, using the same amount of lump charcoal you used, and all but a handful of it burnt up. It locked on 200 degrees until I was asked to leave home for a couple hours, so I closed it down a bit....just in case. Came back to find it had dropped to 175. Back to full open and it came right back to 200, where it stayed the rest of the day. It was still maintaining 200 degrees (with more air added) at 13 hours. As designed, with the ball valve, I think you are right on the edge of perfect and going out.

Your temp loss at an hour could also be due to burning up your initial lighted stuff (from the chimney). That's lit and burns, but the stuff below it may not be getting going from lack of air. Given a choice, I'd say you are better off going too hot vs. too cold (a snuffed fire) from a meat quality standpoint. With an incomplete burn, you start getting creosote buildup, which is not good.

On smaller smokes......like ribs, I don't use a full basket. I put a 1 quart can in the middle and make a ring of charcoal and chunks around it. Then I dump the chimney on top, and it burns down from there. That burns virtually all of it.

In doing some research, Cowboy is supposedly made from drops and scraps at hardwood flooring factories. That's why a lot of it looks like boards. It is!

In theory, that should make it better, but I've been disappointed with it. Being from Missouri.....I have other options.

thestealth · Aug 7, 2009

Not enough air flow? I've never used lump charcoal (or a UDS), it just seems odd that it didn't ignite much of the surrounding chunks.

geek with fire · Aug 7, 2009

To your later point, Cowboy is junk. Pick up Cowboy and another back of lump the same size. You will feel the difference; Cowboy is full of air.

The only other thing, and hard to tell from your pics, but it looks like your basket is pretty wide. Not saying that's wrong, only it's larger than mine. Maybe air can't get up the sides and not allowing even burns. What size is the lower grate. I guess it looks like the standard Weber charcoal grate, but for somke reason it looks large in your drum.

jirodriguez · Aug 7, 2009

Definately get rid of the Cowboy lump. I made the mistake of buying that when I first got my horizontal offset. I got it to light and burn fine, but it had no staying power. I had to add a fresh chimney every 45 minutes, just to keep the temps at 200 for my 6 hr smoke.

pinkmeat · Aug 7, 2009

I had the opposite problem with lump in the UDS> It lit too quickly and temps soared then used all my fuel prematurely. I have gone to briq's in the drum unless I am hot grilling over lump charcoal.

helljack6 · Aug 7, 2009

So tell me if this makes sense. I fired the drum again today, just for the heck of it. It soared well over 300 for the first hour, came down to about 292 during the second hour, and now, after uncapping one intake and setting the magnet back to 1/4 open, my temps are now hanging around 240ish with very mild (1 to 2 degree) temp variations and have been holding that way for about the last hour, been burning since about 2pm too......any ideas as to why now suddenly it works? Using the same fuel that was pictured from earlier too.

ddave · Aug 7, 2009

You're giving it more air this time.

My drum will run all night long (12 midnight to 6:30 am) at around 240° with 2 caps and the ball valve 1/2 to 3/4 open with Kingsford Comp. That stuff really likes to burn. My basket is 13.5" in diameter by 8" tall.

With Cowboy, in the early stages of experimenting with the drum, I had a hard time getting it over 250° with all three intakes wide open. With Lazzari Mesquite lump, it ran best with 1 cap off and valve about 1/2 open. So there is a wide range of "sweet spots" depending on fuel.

I think GwF may have a point. How wide is your basket? If it is a full 18" that may be part of the problem with the fuel not staying lit.

Dave

helljack6 · Aug 7, 2009

My firebasket (i had to remeasure it this morning just to be sure I was accurate) is 6-7" high and about 16.5-17" round.

So, if I understand you correctly, different types/brands of fuel will require different air supply requirements to maintain the same temperature in a given cooking device such as the UDS? That's good information, I wish that would have been something that was touched on over at bbq-brethren in their UDS forum.

I did notice that the setting is relative to what #1's original settings were when I would hold 240ish for extended periods of time before I got rid of it. Now that I have it running right, i'm thinking i'm just going to leave the settings alone whenever I have to fire it so it always has the same amount of air supply to it. Thoughts?

danbury · Aug 8, 2009

I have 2 3/4 ball valves on my UDS and once I start my coals (Royal Oak Steakhouse is my favorite and never ever will I use Cowboy), I always have one valve closed and the other wide open. Once my temp hits 225ish, I close the valve down to about half and tweak a little at a time till it hits and stays where I want it. The stack is one of two. Either the regular lid with a piece of pipe or lately I've been using a Dome lid. Both have very tight seals. Either way the stack is wide open.

Later on once I start getting drippings, depending on how much, either my fire reduces a bit, in which I open the valve a bit at a time or if it starts getting hotter than I want, start shutting it down. Not unusual for my one open valve to be shut down 3/4 closed.

My basket is 17" diameter by I think 7 inches. Can't remember. It sits 1.5" off bottom.

**edit** it is not unusual to have to kick the drum hours later to shake the coals, but I don't have to do that on shorter cooks (6 hours give or take)

billbo · Aug 8, 2009

Normally I need to run one 3/4" intake wide open or 95% at all times depending on wind etc. Sounds like you got her dialed in on the second try there. It may appear to only burn the middle but if you let that thing chug for a couple of days it will burn that fuel up.

I usually start with all three intakes open. Cap one at 200, the second at 225 and see what happens. This method has worked well on my drum.

Throw some meat on there Nutzman and let er eat!

ddave · Aug 8, 2009

Yes. There are differences between different brands of charcoal and lump.

Well, don't lock yourself in to a certain valve position. The drum will run different empty than it will with a 15 pound packer or 2 racks of ribs. If my drum is warming up and stabilized at, say 240° and I toss a big ol' brisket on there, the temp will drop some and I will have to give it more air. As the cook progresses and that big piece of meat comes up to finish temp of 195° or 200°, the drum temp will creep up as well as there is not much of a heat sink in the meat any more. If I'm doing 2 racks of ribs, it will want to creep up sooner since there isn't much mass absorbing the heat.

The main thing I think is to make small adjustments and give them time to take effect - say 30 minutes or so. Also, don't try to maintain too tight a range. I shoot for between 235° and 270° since mine likes to run hot. If it's in that range, I won't bother it. There is also a minimum opening which I will not go under. If I have 2 caps on and the valve only 1/3 to 1/4 open, I will not close it any more -- period. I have done more damage taste wise to the meat by trying to choke the fire down than a high cooking temp would have caused. Once I tried to choke it down and the ribs tasted like they fell in the ashpan. Another time I let it ride, by the end of the cook, side guage said 240° which was probably 290° center grate. I just finished the ribs like I normally would and they were awesome. Now, I don't purposely try to cook that high, but if it's a really hot day and the drum creeps up a bit, I don't worry about it.

Dave

helljack6 · Aug 8, 2009

Yeah, i'm going to work with it some more. I'm taking an un-built barrel into my FIL's place in the morning and we're going to cut a 2" intake into it and weld some pipe with a 90 degree elbow on it and that's going to be #6. The other thing I want to try to figure out is, is it more beneficial to use a 2" bung exhaust or eight 1/2" holes evenly spaced with regards to temp control.

danbury · Aug 8, 2009

On mine I capped the original bung hole on the side and then drilled a 2" hole dead center on the original lid for the pipe stack.
The dome lid has the exhaust sort of high and off center. To be honest, I never saw any difference either way on the original top other than my anal retentiveness of having things centered.

ddave · Aug 8, 2009

My original lid had the eight 1/2 inch holes and it worked very well. But many people are happy with the original bung hole, too.

For the intakes, I'd stick with 3 - 1" holes, 2" off the bottom with 3/4 nipples. Charcoal basket on 3" legs. Not too big, maybe 12" to 13" in diameter and 6" to 8" tall.

I admire you're desire to experiment and being an IT guy, I can understand that. But your going to drive yourself nutz, man.

Sorry, couldn't resist. But seriously, my drum seems to have it's own personality. It ran different when it had eight 1/2" holes in the lid. I increased them to 3/4" and it ran different still. Then when I put the Weber lid on, there was a different sweet spot.

There will be some variablility in the temp especially if you are measuring it with a digital. I don't even pay attention to the digital anymore. I know where the temp should be on the side guage and go from that. Plus Danbury makes a very good point. As the cook progresses it may be necessary to "kick" the drum to shake the ash loose or increase the intake openings a bit.

Good luck with #6.

Dave

helljack6 · Aug 8, 2009

I appreciate all of the feedback. I think it's mostly my anal retentiveness that drives me to find out what works and what doesn't. I'm ALMOST tempted to go back to #4 with the 1/2 intakes and rework the design from there. Yes, I rely on a digital therm on the middle of my grate. Thinking I may go and get a reliable dial therm and stick it in the side and rate the difference in temps and go from there. Dunno, so many possibilities even will still trying to remain in the KISS principle.

ddave · Aug 8, 2009

HA!! Just as I thought.

I used to do the same thing on the drum and used two dgitals in my offset trying to "balance" it. I tell ya, they will drive you CRAZY because they react so fast!!

That's mostly what I do now and the reason for that is one time while I was cooking, I was using my trusty Maverick ET-73 with the probe at the center of the grate. It was cruising at 241° and all of a sudden the hi temp alarm, which was set for 260° starts beeping. So I go running out there ready to change the intake setting when I notice that the dial thermo on the side, had not budged from about 195°. So I go back in and watch the ET-73. In the span of about 3 minutes, the temp drops back down to around 240°. I go back and check the dial thermo and it STILL had not budged.

I'm thinking I had a chunk flare up or something of that nature that the digital was sensitive enough to pick up but that really didn't change the overall temp in the drum. And it corrected itself on its own with no interference or adjustment from me. Now I only use the ET-73 if I need to remotely monitor it and I set the low and high range from about 230° to 270°.

It is fun to experiment but sometimes we can get overloaded with information just because we can track it.

But seriously, have fun with it and don't forget to throw some meat on there once in awhile so you have some good grub to eat.

Dave

helljack6 · Aug 8, 2009

OMG I so think you just nailed my issue on the head. I've been so paranoid with finding that "sweet zone" that I've let it become an agent of control instead of controlling the issue. Gonna switch back to dial therm today and use the digi therm for finding out the difference in temp from the outer to the middle so I know what to shoot for on the dial therm. And then i'm done with it!

On another note, I fired it yesterday and it ran for 12 hour on cowboy lump with a final combustion rate of about 93% based on the couple of small pieces I had left this morning.

hog warden · Aug 8, 2009

On the 8 - 1/2" holes....or larger vs. the one 2 inch bung.......my lid has 2 - 2" bung holes, and I've tried it with with both of them open.

With two big holes like that open on the lid, you can get one hole venting and one drawing, and get an uncontrolled fire going. When that happened, I shut off the bottom vents completely and it didn't matter. It kept going. Funny part was it would shift back and forth between holes, depending on what the wind was doing (wind was swirling around). Wind over the top of the vent stack creates some negative pressure, causing it to draw.

With 8 holes on top, I wonder if you could get some of that. Some venting and some drawing. Perhaps even more so if they are larger?

With only one hole, the vent stack is always venting and supply air has to come from the bottom vents.

ddave · Aug 8, 2009

Sounds like a good plan.

Another thing that folks have done, and I'm in the process of doing it, is using a 12" deep fry thermometer. Take a good sized bolt and put it where the dial therm would normally go. Drill a hole through it that the stem of the deep fry thermometer will just slide through. That way it will measure temp and the center of the drum but you can slide it out to get the charcoal basket in and out. I've got the thermo and the bolt, I just have to get the hole drilled.

Dave

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