In an 11-quart stockpot, combine the potatoes, chorizo, onion, beer, bay leaves, 1 teaspoon salt, and 1/2 teaspoon pepper. Add just enough water to cover the potatoes. Add the corn, shrimp, and clams in layers.
Cover the pot. Cook on grill until the clams open, the shrimp are opaque, and the potatoes are tender, 20 to 25 minutes. (Or cook on the stove over medium-high heat.)
Transfer to a large platter and serve with the bread and butter.
Tip: Yep, clambakes are messy -- especially with all that melted butter. Make yours a little tidier by giving each guest a small bowl of butter, poured from a pitcher. After the meal, pass each guest a bowl filled with water and lemon slices to rinse off sticky fingers.