Preheat oven to 325 degrees. Generously grease two 8 ½â€ x 4 ½â€ loaf pans. Combine flour, salt, baking powder, baking soda, and spices in a bowl; use a whisk to mix well and set aside. In large bowl of an electric mixer, at medium speed, beat butter and sugar until just blended. Add eggs one at a time, beating well after each addition. Continue beating until very light and fluffy, a few minutes. Beat in pumpkin. The mixture might look grainy and curdled at this point -- that's ok. At low speed, beat in flour mixture until well combined. Turn batter into prepared pans, dividing evenly, and bake for 65 – 75 minutes, or until cake tester inserted in center comes out clean. Let loaves cool in pan about 10 minutes, then turn out on wire rack to cool completely. (If the loaves stick, run a plastic knife around the edges of the pan to loosen them.) Fresh out of the oven,the loaves have a deliciously crisp crust. If they last beyond a day, you can toast individual slices to get the same fresh-baked effect.