Combine sugar, salt & spices.
Add pumpkin and sour cream; stir well.
Beat egg yolks until thick and lemon colored; stir into pumpkin mixture.
Beat egg whites (brought to room temperature) until stiff peaks form.
Fold into pumpkin mixture.
Pour into pastry shell.
Bake at 450ºF for 10 minutes.
Reduce heat to 350ºF & bake 50 minutes more, or until set.
Top with whipped cream if desired. Yield: one 9 inch pie.