Preheat oven to 325 degrees F (165 degrees C). Grease a 10 inch tube pan with 2 tablespoons butter. Sprinkle pan with 1/4 cup sugar. Mix together 2 3/4 cups flour, baking powder and salt. Set aside.
In a large bowl, cream together 1 cup butter and 2 cups sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Gradually beat in the flour mixture. Dredge blueberries with remaining 1/4 cup flour, then fold into batter Pour batter into prepared pan.
Bake in the preheated oven for 70 to 80 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely.