14lb is an average packer...I've passed several through the smoke in the 17-18lb range, and countless 15-16lbrs. Where I had to take a step back was when I read "injected". I don't inject intact whole muscle meats, because now you have a compromised muscle which should be handled and cooked in a manner so as to maintain the 40-140*/4-hr guideline for cooking (should pass from 40-140* internal temp, or, danger-zone as we call it, in 4 hours or less) for food safety purposes.
I've never used a pellet smoker, but chamber temps is chamber temp for the most part, where thermal convection efficiency can vary from one type of smoker to another. I would start your smoker @ 250-260* chamber/grate temp to help push that packer through the 40-140* temp a bit faster than normal and this should keep your danger-zone time under 4 hours. This will also cut down on overall cooking time as well, but you can drop back your chamber temps when you approach the 140* internal temp so temp rate climb isn't too fast when you get near the melting temp of connective tissues in the muscles (around 156-164*, if I recall correctly). This help the brisket to get more tender if it can ride longer in the mid-150 to mid 160* range.
Are you planning to slice the entire brisket, slice the flat and pull the point, or sliced flat and burnt ends from the point? Remember, if point/flat cuts are not separated before slicing, you will have slices with the grain on one (tougher chew) and across the grain (more tender) on the other muscle, unless you change direction of slices by 90* angle at some point. Point muscle grain runs across the thickest end of a whole brisket, while the flat muscle grain runs lengthwise on the thinnest end. The point and flat overlap each other about mid-length and taper to a very thin muscle section, while the opposing muscle gets progressively thicker.
For sliced flat, I take the flat to 180-190*, start probing for tenderness @ 180*, take higher if needed. Separate the point from the flat when the point reaches the mid 150's and cube for burnt ends, sauce lightly and return to the smoker on open grates for a couple more hours @ 225* until crispy on the outside...should have a relatively tender, popping chew in the center if cubed-up early enough (not too high of internal temp). For pulled point, take to 200* or a bit higher.
Don't forget to rest the slicing or pulling subject (after reaching finished temps) for a few hours wrapped in foil and towels to insulate for a slow cooling to redistribute the meat's juices.
EDIT: forot to mention...cross-hatch score the fat cap after some light trimming of the tougher spots and corn...this will help to keep the brisket moist as it self-bastes from the rendering fat.
Come on back if I confused you or you're interested in more about pulled point, burnt ends, etc. Lots of posts on all of it if you know how to look...I have several brisket threads here as well and can link them if you like, or check my signature line.
1st briskets may seem overwhelming...don't fear the brisket, just give it it's due respect.
Eric
