Allen shot 8-for-10 for the Owls (10-7, 2-1 Atlantic 10), who connected on 28 of 52 shots. Dionte Christmas, the A-10's leading scorer, sustained a cut over his eye with 13:17 left and did not return.
Tommie Liddell had 12 points for Saint Louis (11-7, 2-2), which was held to its lowest point total of the season. Leading scorer Rusty Lisch, averaging 13.8 points, was held scoreless and missed all 10 of his shots.
The Owls, who hit nine of their first 10 shots, build a 27-7 lead midway through the first half.
Hitting from the inside and outside, Temple raced to a 43-16 halftime advantage. Allen led the way, shooting 6-for-6 from the field.
The closest the Billikens came in the second half was the final 15-point margin.
Saint Louis freshman guard Kwamain Mitchell collided with a teammate with 2:29 left and sustained a neck injury. He was carried off the court and taken to a hospital for observation. There was no immediate word on his condition.