Rookie catcher Ed Hearn hit a three-run home run in the sixth inning to carry the Mets to an 8-5 triumph over the Pittsburgh Pirates and a sweep of a doubleheader yesterday in New York. The Mets won all four games of the series against Pittsburgh and extended their winning streak to six games.

The Mets won the opener, 4-1, as Bob Ojeda scattered nine hits and Len Dykstra went three for four.

"They always get the hit or make the play they need," Pirates Manager Jim Leyland said. "That's why they're a zillion games over .500. We can't get one-out hits to keep a rally going, and they get two-out hits all the time when they need them."

In the second game, New York's Mookie Wilson hit a two-run homer, his fourth of the season, in the third inning, and Gary Carter added a home run, his 11th, in the fourth.

Rick Aguilera (1-3) was the winner as he pitched 5 1/3 innings and allowed three runs. Roger McDowell, the second of two relief pitchers, earned his fifth save.

In the opener, Ojeda (8-2) got his third complete game of the season and lowered his ERA to 2.37, allowing nine hits, walking one and striking out five. He lost his shutout in the ninth when Jim Morrison and Tony Pena had doubles one out apart.

Bob Walk (2-3), making his first start for the Pirates this season after 21 relief outings, took the loss, giving up five hits and three runs in five innings, walking two and striking out four.

Dykstra led New York's offense with three hits, two runs and a stolen base in four at-bats, including a leadoff triple in the sixth.

Giants 7, Astros 2: Jeff Leonard, Chris Brown and Chili Davis each had three hits as San Francisco's victory at the Astrodome cut Houston's lead in the NL West to two games.

Vida Blue (4-3) was the winner with relief help from Jeff Robinson and Mark Davis. Blue pitched six innings and gave up one run on four hits, striking out six and walking one. Bob Knepper (10-4) was the loser, giving up 10 hits and four runs in five innings.

"Bob Knepper's a great pitcher," said Giants Manager Roger Craig after the teams split their four-game series. "But he wasn't sharp with his breaking ball today, and that hurt him."

Brown started things for the Giants in a three-run fourth with a double. Leonard drove in Brown with a single and scored on Davis' triple. Robby Thompson drove in Davis with a squeeze bunt.

The Giants increased their lead to 4-1 in the fifth on Thompson's squeeze bunt with the bases loaded. They added single runs in the sixth, seventh and eighth innings.

Dodgers 6, Padres 0: First baseman Steve Garvey's two-run throwing error on Alex Trevino's bunt single triggered a three-run seventh inning as Los Angeles won in San Diego.

Rick Honeycutt (4-3) pitched six innings for the victory, extending his shutout string to 22 innings.

With the game scoreless, Bill Russell opened the seventh with a single and moved up on a bunt by Franklin Stubbs. Stubbs reached first when catcher Bruce Bochy attempted to get Russell at second.

Trevino then bunted past the pitcher's mound, where Garvey fielded the ball, fell and threw wildly past first as Russell and Stubbs came around to score. Trevino took second on the error and scored on Mariano Duncan's two-out single off reliever Lance McCullers.

Cubs 4, Cardinals 3: Steve Lake's bloop single in the 11th inning scored Keith Moreland from second base, giving Chicago the victory over St. Louis at Wrigley Field.

It was the Cubs' first victory under Gene Michael, who took over as manager Saturday.

With one out in the 11th, Moreland doubled to center and Leon Durham drew an intentional walk. Chris Speier flied deep to left before Lake singled to right as Tito Landrum failed to make a diving catch.

Reds 9, Braves 7: Eric Davis knocked in three runs with a single and a home run as Cincinnati won in Atlanta.

Davis had a two-run single in the first inning and a bases-empty homer in the fourth to pave the way for winner Tom Browning (4-6), who pitched five innings before getting relief help from Scott Terry and Ted Power.

The Reds combined seven hits off Atlanta starter Zane Smith (5-7) with two errors by Atlanta shortstop Rafael Ramirez to score four runs in the first inning and three more in the third.

Dave Parker and Davis then hit home runs off reliever Steve Shields in the fourth for a 9-0 Cincinnati lead before the Braves scored.

Ozzie Virgil's two-out single in the fourth, the first hit off Brown-ing, started Atlanta's four-run rally. Terry Harper's double scored one run and pinch hitter Bruce Benedict's double scored three.

Expos 2, Phillies 0: Herm Winningham hit a home run and Andy McGaffigan allowed four hits over 6 1/3 innings as Montreal won in Philadelphia.

McGaffigan struck out seven and walked two and raised his record to 4-2. Jeff Reardon got his 15th save.

Winningham led off the third inning with his fourth home run of the season off Charlie Hudson (4-4). Montreal added another run in the ninth when Hubie Brooks tripled and stole home.