Danny Heep and Gary Carter homered and Ron Darling allowed eight hits in eight innings to lead the New York Mets to a 6-2 victory over the Astros last night in Houston. The Mets have won 20 of their last 24 games.

Darling (4-0) left after Phil Garner led off the ninth with a single to left. He struck out three and walked two. Jesse Orosco, who has yet to allow a run this season in 12 appearances, got the last three outs.

The Mets took a 1-0 lead in the second inning. Darryl Strawberry walked, stole second, took third on Heep's grounder and scored on Ray Knight's single off Nolan Ryan (3-5).

New York increased its lead to 3-0 in the third. Len Dykstra singled to right with one out and stole second before Howard Johnson walked. Keith Hernandez singled home one run and Strawberry scored another with a sacrifice fly to left.

Heep, a former Astro, hit a two-run homer in the sixth and Carter lined his sixth homer of the season over the left field wall in the eighth.

*Braves 7, Expos 4: Ken Oberkfell hit a three-run home run in the 10th inning to give Atlanta the victory in Montreal.

Oberkfell hit a full-count pitch from left-handed Dan Schatzeder (2-1) over the right field wall for his first homer of the season. It scored Dale Murphy, who had singled, and Bob Horner, who had walked.

"I'm certainly not a home run hitter, but that one came at an opportune time," said Oberkfell, a left-handed hitter who usually does not bat against left-handed pitchers. "You don't expect to see me hit home runs. I don't like sitting on the bench and I'm batting .400 against left-handers. I hope [Braves Manager Chuck Tanner] noticed I hit that homer off a lefty."

Montreal, trailing 4-2, had tied the game in the last of the ninth when Mitch Webster's short fly bounced high on the artificial turf. The ball fell in front of Murphy and bounced over his head, scoring Al Newman and Andre Dawson, both of whom had singled off Bruce Sutter.

*Reds 6, Phillies 5: Ron Oester's three-run homer in the ninth inning gave Cincinnati the victory in Philadelphia.

Dave Concepcion and Buddy Bell started the ninth with singles off reliever Don Carman. Steve Bedrosian (2-2) relieved Carman and got pinch hitter Max Venable to fly to right. But Oester followed with his homer, hitting a 1-1 pitch to score Concepcion and pinch runner Tom Runnells ahead of him.

Winner Ron Robinson (3-0) pitched the last three innings, allowing one hit.