Combine pecans and raisins. Dredge with 1/2 cup flour, stir well; set aside.
Combine remaining 3 1/2 cups flour and spices; set aside.
Cream butter in a large mixing bowl, gradually add sugar, beating until light and fluffy. Add eggs, one at a time, beating well after each addition.
Combine molasses and soda, add to creamed mixture. Add flour mixture to creamed mixture alternately with 1/2 cup bourbon, beginning and ending with flour mixture. Mix well after each addition. Stir in pecan mixture.
Spoon batter into a waxed paper-lined and greased 10 inch tube pan. Bake at 325°F for 2 hours to 2 hours and 15 minutes or until a wooden pick inserted in center comes out clean. Cool completely in pan. Remove from pan.
Moisten several layers of cheesecloth with remaining 1/2 cup bourbon, cover cake completely with cheesecloth. Wrap with foil, store in cool place one week, remoistening cheesecloth as needed.