If you have never roasted a whole pig before, be aware that it is not a quick process. In fact, if your butcher or neighbor gives you an estimate on the time to roast your pig, be prepared for it to take longer than that. Especially if you have a back yard filled with excited guests waiting to taste it. But one thing you should never do is to rush the pig just to placate your ever-rowdier crowds. Plan ahead with some snacks — break out more pretzels and chips. Assure the masses that it will be well worth the wait.
When I was first learning how to roast a whole pig, the guests would be hungry and someone suggested that some parts of the pig were already done. Why not start carving those first. I relinquished and the ensuing half-butchered pig made the grand finish rather anti-climatic. Now I keep the hoards at bay and use that time to socialize, eat chips and snacks, and theatrically build excitement for the grand moment when the meat thermometer declares the pig is at the perfect temperature!
No one can tell you exactly how long it will take your pig to be done. There are estimates that can help but plan on what happens when it is ready a few hours earlier or a few hours later than you think it will be. A rule of thumb is that a 100 lb (that’s live weight) pig on a spit may take 8-10 hours while the same size over slow coals can take over twice as long. A pig roasted in the ground, Hawaiian or Kalua style, can take 12 hours if done right and if it is filled with fruits and vegetables it can take 16 hours or longer.
I typically roast a pig as slowly as possible on a grill over a smokey bed of coals for maximum flavor, juiciness, and tenderness. I use at least 160 lb pig (live weight) and I start it around 5 pm the day before the pig roast. It will slowly cook all night long under the watchful eye of a couple of eager neighbor kids plied with chips and Skittles and sodas that their parents normally restrict. The next morning my wife & I stumble out of bed and relieve the kids (who dubbed themselves, “The Pig Sitters”) of their overnight duty and we take over for the whole day. By 2 or 3 pm guests start arriving and by 4 or 5 pm, the pig is ready to be served — 24 hours after starting it cooking it! The first year we did it this way, the pig wasn’t ready until after 6pm. I’ve gotten better at regulating the coals now to get very close to my target time of 4:30 or 5pm. It takes some experience to do that but I still plan on some flexibility in my schedule in case I don’t hit my target time.
The best investment I made was a good digital meat thermometer. I got a nice one with a wireless remote sensor. (I also kept my manual roasting thermometer handy after one year when the new batteries in my wireless one prematurely died.) With my wireless marvel, I can be on the other side of the yard when someone asks me how the pig is doing. I can take out my wireless thermometer and sagely let them look at the temperature of 120 degrees and tell them it will be ready at 160 degrees.
Depending on how the pig is being cooked and how big the pig is, will determine the time it takes to roast it. But if the meat thermometer shows the temperature is lower than 150 degrees any place on the pig, let the pig continue to cook. If most of the pig is over 160 but there is a place in the center of a ham that is just 150-155 and the guest vultures are circling, I start the serving process. The USDA is now stating that a roasted pig over 145 degrees is safe to serve with at least 3 minutes rest time after that. However, if you serve it at 145 degrees, there will be enough pink to make your guests uneasy. On the other hand, cooking it too much over 160 will start it drying out. Fortunately, a pig is large enough that some of it can be 150 (my favorite temperature) while most of it will be 160 degrees or over which is what most of your guests want to see.
And don’t forget to take into consideration that when you remove the pig from the spit or grill, it will continue to cook as you march it over to the serving table. So don’t rush the setup after removing the pig from the fire. A few extra minutes while putting an apple in the mouth or putting a few decorations around it will give it time for the juices to settle and the meat to become even more tender! And it won’t hurt to let the crowd’s excitement grow for a few more minutes.