Heat oven to 350°F. Butter and flour a 9 x 5-inch loaf pan. In medium bowl, sift all-purpose flour, ground cinnamon, baking soda, baking powder, and salt.
In large bowl, blend sugar; sweet potatoes, drained and mashed; vegetable oil; eggs; and vanilla extract. Stir in dry ingredients, walnuts, and raisins. Transfer batter to pan and bake about 1 hour.