In a large saucepan, combine 1 1/2 cups sugar, cornstarch, egg nog, egg yolks, butter and corn syrup. Cook over medium heat, stirring constantly, until butter melts and custard thickens.
Remove from heat and stir in vanilla extract. Pour into prepared pie shell.
Beat egg whites, cream of tarter and 1/4 tsp salt at high speed of an electric mixer until soft peaks form.
Gradually add 1/2 cup sugar, 1 tablespoon at a time. Beat until stiff peaks form. Spread meringue over filling, sealing to edge of pastry crust.
Bake for 25-28 minutes, until golden brown. Cool completely and store in refrigerator.