This is the recipe that I've been using with good results ...
Boston Baked Beans (traditional Bean Pot method)
1 - 2 1/2-quart bean pot (or covered casserole)
2 pounds beans
1 teaspoon of baking soda
1 pound salt pork (or bacon or ham)
1 medium onion -- peeled and diced into large pieces
8 tablespoons of brown sugar
2/3 cup molasses
2 teaspoon dry mustard
2 teaspoon salt
1/2 teaspoon ground black pepper
Soak beans overnight. In the morning, preheat oven to 325° F. Place the baking soda in a large pot and fill half way with water (about 6 cups). Bring to a boil and add the beans. Boil for 10 minutes. Drain beans in a colander and run cold water through them. Set them aside.
Dice the salt pork (or bacon or ham) into 1-inch squares. Put half of the salt pork on the bottom of the bean pot, along with the onion. Put beans in the pot. Put the remaining salt pork on top of the beans.
Mix the brown sugar, molasses, mustard, salt and pepper with about 3 cups of saved hot water from the beans and pour over top (or add more until the beans are just covered). Cover pot with lid and place the pot into the preheated oven. Bake for about 6 hours. Check pot periodically to check the amount of liquid remaining. Add a bit of water to the beans slowly as needed to keep them moist, but do not flood them. Remove the pot from the oven and serve warm.