85 gallon UDS questions

I have three 3/4 inch holes for the intake. I put close nipples in the holes and secured them with lock nuts on either side. I installed a 3/4 inch ball valve on one of the nipples, and I use caps for the other two. I’m thinking of enlarging the ball valve to a 1 inch. As for exhaust, my drum is a 55 gallon, and a 22 1/2 inch Weber kettle lid fits perfect. So I just use the butterfly vent on the lid.

When I got into cooking on drums (2005 or 2006) I should have purchased a stainless steel one, they were still expensive but way less than they are today. You made a good score.

Have you done a test cook or two or just thinking you want more intake? My drums are the same diameter as a 55 gallon, but they are about 5" taller (so maybe they are 65 gallon?) anyways I only have three intakes, and I believe they are 3/4", and a series of smaller exhaust holes in the lid. All take the conduit knock-outs. I'll measure them later this morning. Plenty of folks use ball valves, but my drums draft just fine. If you go the ball valve route, I would keep at least one knock-out so you can use a wiggle rod on the charcoal basket.

Originally I took some spare intake knock-outs (which have a flat face) and drilled holes in the center to fine tune the intake, then I switched to 1" square rubber magnets I can slide over the intake holes which give me even finer adjustments... now, if your drum is 304 stainless it won't be magnetic. I'd check it with a magnet just in case, some breeds of stainless are magnetic.

I have two grate heights, that seem in line with your drum, I'll check that dimension as well. I rarely cook with both grates, because at some point I was rotating them. Weber has a 26" grill grate, but the actual size of the grate is 25.4", I think these fit the 85 gallon drums. But you need to confirm this.

You will have to do some Googling for your grates.
There are some to be had- you may not care for the prices.

If you have one grate already, I'd cook on that and call it a day. Everyone seems to like the idea of loading up 2 grates- and it sort of is...once.

How many times have you used it? Do you have issues coming up to a particular temp?

Here is what I can share on those dimensions: My lid has a hole pattern of 8 exhaust vent holes, they are 1/2" in diameter and the knock-out plugs are convex (dome shaped) like little buttons. My 3 intake holes are actual of 7/8", but that might be to allow easier removal and replacement of a 3/4" knock-out. Those knock-outs have a flat face. Some people put a small bolt in the knock-out as a handle when removing. My upper grate is 7" down from the rim, and the lower grate is 14" down from the rim.

Here is what my 3/4" plugs look like. They come in a 4-pack for $1.61 at Home Depot.

Maybe keep the holes you have for the KO plugs - add a 3/4" full port ball valve and call it a day for the intakes.

To me, 8 x 1/2" holes is not enough exhaust. 8 holes that size only works out to 1.5" sq inches. That's less than a Weber Daisy wheel.

My favorite UDS had the flat lid and a 2" bung. That bung had a 3.14 sq" area.

Bigger /more intakes don't mean much if the hot air can't exit.

OR just don't stress over 225.

$300.00 for a SS 85 gallon uds - ready to cook? Bargain bordering on a steal.

IF you want magnets, you can still do that- you just have to provide a fitting for the magnet to stick to. Pop in a threaded elbow ("street elbow"), secure with an appropriate sized washer and conduit nut - Bob's your uncle!

I used sliders on my 30 gallon and 50 gallon UDS(s) - but I'd have no problem going with street 90's and round magnets on a future build.

Good luck.

mw3538 said:

I have made several cooks on the drum. Seem to have a harder time keeping temp in the 225 range for extended period of time. Do get a bit of white smoke. Looking to get it more consistent on the temps. Got her nailed for 275/280 for ribs.

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Drums tend to have a sweet spot where they like to run on their own, mine like 260° and 280°, it's possible but tough to catch and hold a 250° or a 275° so I let em' ride. You will drive yourself crazy worrying over +/- 10°.

As far as white smoke.... drums produce white smoke because of the little flavor bombs of fat dripping into the coals, just like real open pit bar-b-que. :mrgreen: I let my fire settle in for an hour or so and I see clean smoke..., then add the meat and the white smoke returns. You will get the sweet blue toward the end of the cook. I've got 4 briskets cooking here and they are at about hour 5 or 6.

Nuco59 said:

Maybe keep the holes you have for the KO plugs - add a 3/4" full port ball valve and call it a day for the intakes.

To me, 8 x 1/2" holes is not enough exhaust. 8 holes that size only works out to 1.5" sq inches. That's less than a Weber Daisy wheel.

My favorite UDS had the flat lid and a 2" bung. That bung had a 3.14 sq" area.

Bigger /more intakes don't mean much if the hot air can't exit.

Click to expand...

I don't have any problems with the eight 1/2" lid vents on my drums, but the volume, diameter and height of an 85 gallon drum could change the draft.

mw3538, if you want to increase your exhaust you could always use a step bit and carefully open up the 1/2" lid vents to 3/4 (or slightly larger) which would give you 3.5 sq/in of lid vents, which is more than Nuco59 prefers. And... instead of adding a ball valve, add a couple more 3/4 intake holes and use the same plugs. I like to rotate my intake plugs so I get an more even burn in my basket. I also wiggle my charcoal after 2 or 3 hours, then again at 6 to 8 hours into a cook.

Nuco59 said:

$300.00 for a SS 85 gallon uds - ready to cook? Bargain bordering on a steal.

IF you want magnets, you can still do that- you just have to provide a fitting for the magnet to stick to. Pop in a threaded elbow ("street elbow"), secure with an appropriate sized washer and conduit nut - Bob's your uncle!

I used sliders on my 30 gallon and 50 gallon UDS(s) - but I'd have no problem going with street 90's and round magnets on a future build.

Good luck.

Click to expand...

Instead of a street elbow, what about a waste nut? They are threaded, magnetic and work good for mounting a valve or in this case a BBQ Guru fan coupling. If I ever get around to adding a forced draft system to either of my drums, I think this one way to roll.

My preference for more exhaust has more to do with coming to temp or hitting a higher temp. I've seen lots of builds that used the half inch holes. I do think that layout has more even grate temps... I just like the 2" bung more- it's KISS. That straight adapter would work great... I tend to think of options that I can score at HD or Lowe's. I'm sure it will all turn out great. Keep us posted.

Nuco59 said:

My preference for more exhaust has more to do with coming to temp or hitting a higher temp. I've seen lots of builds that used the half inch holes. I do think that layout has more even grate temps... I just like the 2" bung more- it's KISS. That straight adapter would work great... I tend to think of options that I can score at HD or Lowe's. I'm sure it will all turn out great. Keep us posted.

Click to expand...

The circular arrangement of lid vents is one of the early accepted designs, and by default I agree about the even temps and swirl of the flavor smoke/heat, but I've never cooked on a drum with another upper vent option, so I'm biased.