Salvitti secured the win with a foul shot with 9.1 seconds left. PW then missed a shot at the buzzer.
Kelly finished with 16 points, 13 coming in the first half. Central Bucks West held the Colonials to zero points in the second quarter.
"I'm real happy for the kids - they worked hard all year," Bucks coach Adam Sherman said.
Also in the second round:
Matt Penecale poured in 16 points to send seventh-seeded Abington past No. 23 Haverford High, 53-34. The junior guard shot 6 for 9 from the field and grabbed six rebounds. Senior forward Lazaros Mackrides added five rebounds, and Anthony Lee scored 13 points on 6-for-12 shooting.
Mahir Johnson scored eight of his 15 points in the third quarter, and second-seeded Chester surged past No. 18 Souderton, 64-33, at home. Tyrell Sturdivant added 10 points, half of which came in the first quarter.
Top-seeded Conestoga rolled at home against No. 17 Methacton, 45-40, thanks to Zach Jenkins' 11 points and Justin Ardman's 10.
Host Pennsbury, the fifth seed, eased past No. 12 Oxford, 67-50, behind Mekhi Bryant's 19 points.
Alex Epps-Ortiz scored 16 points, grabbed 16 rebounds and added three blocks to lead host Spring-Ford, the fourth seed, past No. 20 Harriton, 61-48. Drew Kakareka had nine points and eight assists.
Public. They split their two previous meetings by a combined four points, yet Martin Luther King had little trouble with Math, Civics and Sciences as the Cougars rolled, 75-56, in the league semifinals at Southern.
Junior guard Sammy Foreman led the way with 17 points and 11 rebounds. Jahmir Taylor, a 6-foot-8 center, grabbed 15 rebounds and recorded seven blocks.
"We were really focused. We just put it together," coach Sean Colson said.
In the other semifinal, Haneef Vaughn grabbed a rebound with 10 seconds left to seal Constitution's 69-65 win over Philadelphia Electrical. Floyd Preito led the Generals with 19 points, and Ahmad Gilbert added 15.
Pa. Independent Schools. Terry Larrier, a senior guard, scored 32 points and grabbed eight rebounds to lead Phelps past visiting Academy of the New Church, 82-66, in the quarterfinals. Raheem Hall added 14 points and six assists.