In medium saucepan over low heat, stir together sugar, milk and eggs. Cook, stirring continuously, until mixture thickens enough to coat the back of a metal spoon, 10 to 20 minutes. Remove from heat and let cool.
In a medium bowl, whip cream with electric mixer until soft peaks form. Beat in vanilla and lemon juice and whip until stiff peaks form. Fold whipped cream into cooled custard. Chill in refrigerator 8 hours or overnight.
Stir chilled mixture and freeze in ice cream maker according to manufacturer's instructions.