Preheat oven to 350 degrees F (175 degrees C). Wash sweet potatoes, slice lengthwise and place on a lightly greased baking sheet. Bake in preheated oven until tender, about 30 minutes. Let cool, peel and mash.
In a large mixing bowl, beat together sugar, eggs and oil. Stir in orange juice and 2 cups mashed sweet potatoes. In a separate bowl, mix together flour, salt, baking soda, cinnamon, nutmeg, allspice and cloves. Stir flour mixture into egg/sweet potato mixture until just combined. Fold in pecans if desired. Pour batter into prepared pans.
Bake in preheated oven for 1 hour, or until golden brown and a toothpick inserted into center of a loaf comes out clean.