For pastry, in a bowl stir together the 1-1/4 cups flour and salt. Cut in shortening until pieces are the size of small peas. Stir in finely chopped pecans. Sprinkle 1 tablespoon of the water over part of the mixture; gently toss with a fork. Push to side of bowl. Repeat until all is moistened. Form dough into a ball.
On a lightly floured surface, flatten dough with your hands. Roll dough from center to edges, forming a circle about 12 inches in diameter. Wrap pastry around a rolling pin. Unroll pastry into a 9-inch pie plate. Ease pastry into pie plate, being careful not to stretch pastry. Trim pastry to 1/2 inch beyond edge of pie plate; fold under extra pastry. Make a fluted edge. Do not prick pastry.
For filling, in a mixing bowl beat eggs lightly with a rotary beater until combined. Stir in corn syrup, sugar, margarine, the 1 tablespoon flour, the bourbon, and vanilla. Mix well. Stir in the pecan halves.
Place pastry-lined pie plate on the oven rack. Pour the filling into the pastry-lined pie plate. Cover edge of pie with foil. Bake in a 350 degree oven for 25 minutes. Remove foil; bake for 20 to 25 minutes more or until a knife inserted near the center comes out clean. Cool.
Serve with whipped cream. Cover and chill to store. Makes 8 servings.