The Wolfpack (2-0) improved to 19-1 against the Pirates (2-1), who lost for the first time under new coach Jeff Lebo.
Not that it mattered much. The Wolfpack's young players took control with less than six minutes to play in the first half and trailing 23-22. They followed with a 42-10 burst that lasted nearly 15 minutes and spanned halftime.
Brown scored 11 points in the charge that put North Carolina State ahead 64-33 with 12 minutes left.
Corvonn Gaines had 11 points to lead East Carolina.
Painter, a sophomore, had 12 points and 10 rebounds while Harrow, a freshman, had 11 points and 10 assists.
North Carolina State takes on George Mason, a 78-56 winner over Charlotte, in Friday night's semifinals.
The Wolfpack and coach Sidney Lowe seem to thrive at events like this. Three years ago, North Carolina State won the Old Spice Classic in Orlando, Fla., and beat ranked Villanova to take the title.
Last year, the Wolfpack did it again in going 4-0 at the Glenn Wilkes Classic in Daytona Beaach, Fla., including a 60-58 win over Lebo's Auburn Tigers in the final game.
The Pirates hung with North Carolina State and moved in front 23-22 on Gaines' two foul shots with 5:33 left.
Then little went right for East Carolina. They missed nine of their final 13 attempts and could not slow down the surging Wolfpack. C.J. Williams had three buckets and Brown 3 points as North Carolina State closed the half with a 15-6 run.
Things only got worse for East Carolina after halftime as the Wolfpack hit nine consecutive shots -- most from in close -- to build their large lead.
Lebo had finally seen enough, drawing a technical with 12:33 to go as he yelled at an official.
East Carolina's high point in the second half may have been freshman Robert Sampson's high-skying jam of a missed shot. Sampson is the son of former Virginia and Houston Rockets star Ralph Sampson.
The only negative for North Carolina State was Smith's condition. He went to the locker room in the first half and came out with his left leg heavily taped. He mostly sat on the bench and limped to team huddles during timeouts.
Gonzalez was whistled for two quick fouls in each half and played just 10 minutes.