Rookie Rickey Henderson's sacrifice fly capped a three-run Oakland eighth inning tonight as the A's downed the Baltimore Orioles, 7-6, before the customary walk-in traffic in 1,880 persons.

The A's were behind, 6-4, when Oriole reliever Sammy Stewart hit Jim Essian with a pitch to lead off the eighth.

Essian moved to second on a ground out, but then Stewart hit Jeff Newman on the hand. Oriole Manager Earl Weaver was thrown out of the game for arguing Newman had swung.

Tony Armas knocked Stewart out of the game with an RBI double and Mike Edwards greeted Oriole reliever Tippy Martinez with a game-tying sngle. Henderson's sacrifice scored Armas.

Oriole starting pitcher Steve Stone, usually undone by the long ball, found the grounder his nemesis in the first inning. Wayne Gross trickled one between first and second and went to third on another ground ball, this one hit by Mitch Page. It traveled just beyond Kiko Garcia's glove.

Essian followed with a carbon copy just pass Doug DeCinces' mitt to score Gross. Mike Heath then became the only A to hit the ball well in the inning, sending a soft fly to center to bring home Page.

A's starter Rick Langford looked sharp through the first two innings, retiring the first six Orioles in order, and Stone settled down in the second, still trailing, 2-0.

The long-ball haunt finally made it appearance in the third, as three A's took Stone pitches deep. Two were caught near the wall, but the third became Essian's sixth home run of the year and second in two games, making it 3-0.

Langford retired the Birds in order again in the fourth, and Stone, surviving a two-base error by Garcia, got out of the inning on a doubleplay.

Langford's spell evaporated in the fifth. Eddie Murray led off with a single and John Lowenstein walked. DeCinces singled to right and Murray scored from second, sliding under Newman's tag.

Gross' boot turned a potential double play minto a force on Lowenstein at third. Rob Picciolo's misplay of Rich Dauer's grounder loaded the bases. Rick Dempsey's deep fly to center scored DeCinces, and when Al Bumbry singled to left, Gary Roenicke scored to tie the game at 3.

The Orioles went ahead, 6-3, in the sixth when Ken Singleton and Murray doubled and Lowenstein homered to right center.

Newman homered off Stone in the bottom of the inning to make it 6-4.