Eric -
The amount of brown sugar I used was more than 20% of the mix. Next batch I may try half the rack with no sugar and half with a reduced sugar mix and not go over 225* and see what that gets me. One thing for sure, the small green egg is a very dry environment and I don't have room for a water pan. That
WSM is looking better and better.
Ah, OK, yea, I see several things working against you. I wasn't aware of the green egg being part of the equation, and being a drier smoke chamber humidity will come into play. Some smokers do fine without additional water, and some don't...if you see a ton of steam coming off the vent throughout the smoke during cool weather, then you're probably maintaining a higher humidity, but that's only one way of measuring it visually. If meat is coming out dry when it's cooked to minimum recommended temp (example: chicken breast or pork loin), then low smoke chamber humidity may very well be the culprit.
Doing a side-by-side with reduced-sugar rub along with a no-sugar rub will definitely tell you alot more about the big picture, as well...good plan! If you can keep both comparison pieces on the same grate will be even better, just so you don't have grate temp variances to sour the trial run. Maybe just a half-slab of each dry rub on the same grate, if you have to, just for the sake of fitting it onto one grate. Every vertical smoker I have runs different temps from one grate position to the next (some not as radical as others), but the variances are always there.
Don't know what your feelings are about foiling ribs, but as a last resort, that will maintain a ton of moisture for you, and all it takes is the last 1-2 hours...the last 1/3 of the total cooking time is where the moisture loss really seems to make a huge difference. Of course, with foil comes the loss of bark formation, or softening of it, at the very least. But, without a water pan, this could help quite a bit. I just wouldn't do it until you finish your investigation on the dry rub. Too many things changed at one time before you really have an idea what is causing the issue, and you won't know for sure what you did that fixed it...that's when you (at least I) start second guessing things and end up with a jigsaw puzzle to figure out. One piece of the puzzle at a time is alot easier to manage.
If you can place a probe just beneathe the grate in the center between the slabs of ribs, that should give the best readings for grate temp. I still do that now and then, even with a smoker I know quite well, just to verify my smoke chamber vs grate temp for reference. That slso tells me if I'm due for a calibration of the analog smoke chamber thermometer.
Yea, the
WSM gets rave reviews...I can't really justify one, myself. I have 3 vertical smokers and 1 horizontal, and I only use 2...one vertical gasser has been decomissioned for upgrading/maintenance, and the charcoal horizontal is converted to char-grilling only. On top of that, I have 2 kids out of the nest, so to speak (1 away for school & 1 working /schooling locally), so my bigger smokers only come around a few times each year.
I think you'll be able to narrow it down alot better now, though. Stick with your side-by-side comparison...that will speak volumes about what's going on with the rub, and that's a very likely suspect, IMO. Something to consider later on down the road: if the dry rub sugar content appeared to be too high in your current smoker, it might have been fine with higher smoke chamber humidity, so don't completely trash the recipe from your notes/hard drive, ect...it may still be a valid recipe if conditions change with the smoke chamber. It is all connected in the end, and more than we know, often times. I've had some dry rubs work out great in one smoker, and then a month or so later, it had me scratching my head when I smoked the identical meat/rub in another smoker. Different fuel type can sometimes make all the difference, then, humidity will change from one smoker to the next, and the list goes on...
Crap...I got long-winded there...anyway, you're on your way, just keep tryin'!
Eric