Sift flour, baking soda, cinnamon and salt together; set aside.
In a large bowl, beat eggs. Add oil, buttermilk, sugar and vanilla and mix well. Add flour mixture, pineapple, carrots, coconut, raisins and walnuts and stir well.
Pour into prepared pan. Bake 45 to 55 minutes or until a toothpick inserted in the center comes out clean.