DETROIT -- Chris Davis sent a pitch to opposite field over the left-field fence and pulled another one deep into the right-field seats.
Davis, who had a two-run homer in Baltimore's six-run fourth inning, hit his second two-run shot in the ninth off embattled reliever Jose Valverde.
"It split right into my barrel," Davis said.
Baltimore improved to a season-high 11 games over .500 by winning its seventh series, including two against the AL Central-leading Tigers, in a month to prevent AL-leading Boston from building a big lead in the East.
"We're doing a lot of things right," Davis said.
Chris Tillman (8-2) gave up three runs and seven hits over five-plus innings. He became the third pitcher in franchise history to win his first six decisions on the road, joining Jeff Ballard (1989) and Hoyt Wilhelm (1959).
Tillman gave up two singles and a walk in the first, but didn't give up a run because Austin Jackson was caught stealing second and Victor Martinez struck out to end the inning with Miguel Cabrera and Prince Fielder on base.
"Tilly wasn't carrying his usual stuff," Orioles manager Buck Showalter said. "It was a credit to him to get through five-plus."
Rick Porcello (4-4) allowed six runs on nine hits, giving up a pair of homers for the third time this year.
Tigers manager Jim Leyland lamented that Porcello seemed to get rattled by Ryan Flaherty's infield hit, which potentially could've been an inning-ending groundout in the fourth, that led to Taylor Teagarden's first homer of the season two pitches later.
"Rick lost his composure a little bit after Flaherty hit that little nubber to third," Leyland said. "Groundball pitchers are going to give up hits like that, and they have to bounce back from them. He should have been able to do that, especially against that part of the order. Giving up a two-run homer to that guy, you can understand, but you have to get out of that inning."
Valverde has given up six homers and 11 runs in 7 1/3 innings over his last seven outings since May 31 at Baltimore, where he blew a save and lost a game by giving up four runs in the ninth.
Leyland deflected a question about whether the team has to make a move with Valverde, saying that decision would be up to general manager Dave Dombrowski.
"I don't think that's something we want to talk about today," he said.
Detroit's only source of encouragement in the series finale was Cabrera, who had two hits to become the first player to have at least 100 hits and 71 RBIs through his team's first 70 games since Boston's Ted Williams in 1948, according to STATS.
Porcello started off pitching three scoreless innings, giving up just two hits, before the Orioles scored six runs on seven hits in the fourth inning.
Omar Infante hit an RBI double in the fourth and pinch-hitter Matt Tuiasosopo -- the first to face Baltimore reliever T.J. McFarland -- hit a two-run double in the sixth to pull Detroit within three runs.
Baltimore restored its cushion the next inning, scoring three runs to take a 9-3 lead.
Valverde entered the game in a low-pressure, non-save situation down by six runs and failed miserably. He gave up three hits -- including Adam Jones' two-run double -- in five pitches and was booed by the fans who were still sticking around to see the end. Valverde kept his 10th pitch down, but Davis sent it deep into the right-field seats to lift the Orioles to their highest number of runs since a 14-8 win Aug. 10, 2010, against Cleveland.
After an off day Thursday in Toronto, the Orioles plan to start RHP Jason Hammel on Friday and RHP Miguel Gonzalez on Saturday against the Blue Jays. ... Detroit will open a four-game series at home against Boston on Thursday with LHP Jose Alvarez making his second career start against RHP John Lackey of the Red Sox. ... Baltimore has been slightly better on the road (22-16) than at home (20-15) this year. ... Detroit dropped its second straight game in Comerica Park after winning 10 of 13 at home. ... Davis had his second multihomer game of the season and the fifth of his career.