Hello. I know my profile says "England" but I didn't get here until I was 50. Texas born and bred. I am NOT the brisket guru. I just want to see if we can take the mystery out of smoking briskets.
Well, reading your method would be helpful but we will start here. I don't know your experience either so we start with the basics. Sorry if you already know some of this. I will also post some links to threads by my friend gary s.. He did a couple very good thread on briskets. We smoke briskets ALMOST the same way; slight differences. I hope others will offer their advice.
First thing is get yourself a good dual probe digital therm.. Most members recommend the Maverick 732-733. The therms in the lid can be WAY off. That may be the whole source of the problem but I'll continue.
You need to do a few modifications to that smoker to help with temp control. Off sets can be tough to get to grips with. Without meat, get a fire going in there to create smoke. Small fire, BIG smoke! NO meat. You can even spray a little water on the coals to create BIG white smoke. What you want to do is see where the smoke leaks are. Mark the leaks, open the lid and allow the fire to burn down or go out. When the smoker cools seal every leak you can using stove rope, high temp silicone, bbq gasket and such. Next, if you have a thin flimsy fire grate use it as a template and build or have built a grate out of 1/2" concrete reinforcing steel ( rebar ). That thin grate will sag with heat and will rest on the ash cutting off air flow to your coals. No air flow no heat. Other option is build a charcoal basket. You can find baskets in the build section. Leave that exhaust fully open and use the intake vent to control the heat. Last tip is go buy a cheap garden trowel. Knock the wooden handle off and weld a 2-2 1/2' piece of that rebar to the shovel. Now you can gently scoop out the ash without them blowing all over your meat and you won't burn your hands.
I only ever did whole packer briskets. I think the flat alone too easily dries out. The quality of the beef will affect the finished product. Different parts of the country are known for different smoked meat and styles. For Texas it is sliced brisket. Not pulled, that is for pulled pork. I slice pork butt but that’s another story. I have been smoking brisket for almost 40 years and as I am OLD school and from south Texas; I am going to give you my take on traditional smoked Tx. style sliced brisket. I still learn a trick or two every time I cook but this is how I learned it. This may sound boring as no rubs are used, but trust me, folks were doing brisket like this a long time and the taste of a traditional, properly cooked and smoked brisket is a thing you will not forget. I do not trim my brisket before smoking, I trim when I slice. I smoke all large cuts fat side up ( thought being the fat bastes the meat ). I do not use rubs, salt and black pepper or cayenne pepper only. Add more than you think you need, it's a big hunk of beef and much of it comes off as the fat melts. I season the meat as the smoker comes up to temp. I do not add sauce. I serve it on the side. I try to let the taste of the meat and smoke shine. IMHO rubs and sauces can detract from the taste of the meat. Quality brisket does not need to have the taste hidden. I do sometimes mop/baste to add a slight flavor change. Bark belongs on Carolina style pulled pork, not sliced brisket as it CAN be hard and tough on sliced brisket. I don’t foil until the rest period. I would say that IF you are going to foil and continue to cook a mop is NOT necessary because you will probably add some sort of Au Jus to the foil , but if you want to mop to add a certain flavor it ain't gonna hurt it. I don’t do burnt ends ( but they ARE good ). The conventional method calls for a temp of around 225 but I would run the temp round 300 – 350 ( if you can't reach that temp in your smoker no prob just use 225 and add a little time ). Pull it off the smoker at 190-195 IT and rest for at least 2 hours wrapped in foil and towels or blanket. I turn brisket about every 1 1/2 hrs.. Wood SHOULD be mesquite by tradition, but pecan, oak, and hickory are good ( in that order IMHO ). A mix of Pecan , Oak and cherry is good. Having said all that I must admit ( if lightning doesn’t strike me ) that this is not the ONLY way to achieve a great tasting brisket. This is all personal preference based on tradition. If you LIKE rubs and sauces then by ALL means add them. MANY threads here to help you with those. Chef Jimmy J has a good au jus recipe. Brisket is really pretty easy but the KEY!!!! to brisket is patience, and patience, and more patience; and no peeking; LEAVE THAT DOOR CLOSED! Buy a good dual probe therm and use it. My MAIN advice is to write down everything. Weight, temp, rub, mop, wood, time, foil/no foil, and anything else you can think of including weather conditions. Next time you will have options to change whatever. Find what you and the family like and stick with it. Sorry for the novel. Good luck. Be sure to let us know how it turns out as we are a nosey bunch, and don't forget the Q-view. Good luck. Keep Smokin!