Joe Montana, adjusting quickly to the new flak jacket protecting his ribs, threw a pair of touchdown passes in the second period to give the unbeaten San Francisco 49ers a 14-5 victory today over the Atlanta Falcons.

Montana returned to action after missing one game because of bruised ribs. His scoring passes, both coming after 80-yard drives, went five yards to tight end Russ Francis and 21 yards to wide receiver Mike Wilson.

Wendell Tyler rushed for 99 yards for San Francisco, making his season total 477.

The defense of San Francisco played its second straight game without allowing a touchdown. Atlanta's offense was inside the 49ers' 10-yard line four times without scoring a touchdown.

In the closing seconds of the game, Steve Bartkowski of Atlanta threw an eight-yard touchdown pass to Alfred Jackson, but the play was nullified by a holding penalty.

On the three earlier drives inside the 10, Atlanta got a field goal, lost the ball on a fumble by Lynn Cain, and was stopped on downs when Gerald Riggs was tackled inches short of the end zone.

Riggs went into the game with an NFL-leading 483 yards rushing and added 136 today.

The 49ers moved ahead, 14-3, late in the quarter. Tyler, who gained 96 yards on eight carries in his best half since coming to the 49ers, keyed the drive by busting a quick trap up the middle for a 40-yard gain. Montana finished the 80-yard drive with a 21-yard scoring strike to Mike Wilson.

Atlanta (2-3) went into the game as the highest scoring team in the National Football Conference, averaging 30.5 points per game this season.

The Falcons scored in the first period on a 22-yard field goal by Mick Luckhurst, and they got their final two points with 1:45 left in the game when punter Max Runager of the 49ers stayed in the end zone for an intentional safety.

The 49ers, who were already thin on defense because of injuries, lost backup safety Tom Holmoe with a concussion and starting nose guard Manu Tuiasosopo with bruised ribs.

Bartkowski, intercepted only three times earlier this season, was intercepted twice by the 49ers. Safety Carlton Williamson picked off a pass at the goal line after Atlanta drove to the 18 early in the fourth period.

The 5-0 record of the 49ers matches the best start in their history, achieved in 1952.