Pork shoulder is an inexpensive, tough cut of meat that benefits from long cooking times to render the meat fall-apart tender. If you don't cook it long enough, you will get stuck with rare pork. Cook it too long and the meat will dry out. Grilling, or smoking the pork on the grill, is a solid way to add lots of flavor while reducing fat. On a grill, fat drips away from the meat, unlike with baking or simmering.
Grilling and Smoking
When cooking a pork shoulder on the grill, it is important to smoke the pork rather than simply grill it. Pork shoulder contains a lot of fat and connective tissues that makes it tough if you apply high heat directly to the meat. Smoking is a low heat cooking process that helps melt the collagen in the meat until the pork is tender. Smoking your pork shoulder is possible with a normal grill, with the main difference being time. Smoking a pork shoulder takes several hours, while grilling would only take several minutes.
The USDA recommends that you cook pork to an internal temperature of at least 160 degrees Fahrenheit in order to kill the bacteria found in raw pork, which can lead to food borne illness. While 160 degrees is suitable for pork chops and thinner cuts, pork shoulder is heated to an internal temperature of approximately 185 degrees Fahrenheit. At this high temperature, the tough parts of the shoulder tenderize and break down.
Grill temperature and the size of the pork shoulder are the biggest factors in determining grill time. However, for basic planning purposes consider that a 6-pound pork shoulder cooked at 325 degrees Fahrenheit should take approximately 3 hours to reach 145 degrees Fahrenheit. Larger pieces will take longer. The best way to know if your pork shoulder is done is to use a meat thermometer, preferably one that has a sensor attached to a long heatproof wire and display so you can monitor the temperature without constantly jabbing the meat or removing the grill lid. The USDA suggests you let the meat rest for 3 minutes when it comes out of the oven before you cut it.
Because of pork shoulder's long cooking time, consider a few ways to add flavor. Marinading the pork shoulder for several hours in a brine, or salt water mixture, can help tenderize the meat and keep it moist on the grill. Add water-soaked hardwood chips to your grill to produce plenty of smoke. Over several hours, the flavors of the smoke will infuse into the pork.