Page 203 - Turkey Book from Meathead

If you are not using a leave-in probe, spot check the temperature with a good digital instant read thermometer by inserting the probe into the deepest part of the breast. Push the tip past the center and pull it out slowly. The lowest temp is the one to watch for. You can do this occasionally as needed. You won't harm anything by peeking. If necessary, add a quart of boiling water to the gravy pan. Don't add cold water or you can cool o the cooking chamber. Make sure there are at least 2 inches of liquid in the pan at all times. Do not let the onions and other solids in the pan burn! Let them get dark, but not black. While you're under the hood, if you are using charcoal add another 15 to 20 chunks every hour. Resist the temptation to reach for the wood chips. The charcoal will make enough smoke.
If you fear that the bird is progressing too slowly and you are having trouble keeping the temp up to 325°F, preheat your indoor oven to 325°F and move the bird and the gravy pan inside. Finishing it this way is fine. You will not lose your pitmaster card. The smoke flavor is already on the bird so now your focus must be on making sure it is not under- or overcooked.
16| Finishing the bird. As the meat temp approaches 160°F, tilt the bird and drain the cavity into the gravy pan below. Now check temps all over, especially the back which can be a bit soggy or even undercooked if it is very close to the water. If the back isn't 160°F, remove the gravy pan and put the bird over direct heat to firm it up (or just leave it in your indoor oven a bit longer). This should take no more than 20 minutes or so, but watch things, because without that buer