The Orioles had a whole day Monday to recover from jet lag after their lackluster, 6-5 West Coast swing, but the day off did nothing to relieve a malady of longer standing--one-run lag.

After a distressing 8-7 loss to the lowly Minnesota Twins tonight, veteran Ken Singleton stood in the quiet Orioles' dressing room and expounded on a basic of baseball. "I don't know what our record is in one-run games," said the slugger, "but I know it isn't good. Last year it was among the best."

With tonight's defeat before 10,998 at Memorial Stadium the Orioles in fact stood at 2-8 in one-run games. "Pennant winners are teams that win about 40 of them a year," said Singleton when appraised of the sad statistic. "That means we've got about 38 to go."

The Orioles came close tonight, within two feet of a tie game, in fact, when Singleton sent a line drive against the wall in left with two out and a man on and the score 8-6 in the bottom of the ninth.

The ball caromed off off the wall within a couple of feet of the top and a fan reaching down to snatch it barely missed. Instead of a score-tying two-run homer, as it might have been had the fan made the catch, it was a near-miss double, one run scoring to make it 8-7. Gary Roenicke popped up to end the threat and the game.

The Orioles thus managed to squander a three home run performance, with three solo shots, the first by John Lowenstein (his seventh of the year), followed by Terry Crowley (his first) and pinch hitter Jim Dwyer's to lead off the ninth inning.

The problem tonight was pitching. Starter Dennis Martinez gave up three runs and six hits in 2 1/3 innings. He gave way to reliever Jim Palmer, who went only two innings before yielding a monstrous three-run homer to Tom Brunansky, a hero-sized outfielder who sent the ball 50 feet beyond the left-center wall at the 387-foot mark.

Palmer gave over to bullpen ace Ross Grimsley, who handled himself respectably, giving up a run and six hits before turning the show over to Tim Stoddard with a man on second and none out in the ninth.

Stoddard promptly gave up an RBI single to John Castino for the eighth and decisive run, which was charged to Grimsley.

Palmer took the loss, having given up the runs that put Minnesota ahead to stay. His record is 1-2. The winner was Bobby Castillo (2-1).

The loss is a bitter pill for the struggling Orioles, who have been hanging around the American League East cellar since their horrific nine-straight loss streak in April.

The plan has been to mop up on easy opponents before heading off against New York, Detroit and Milwaukee next month.

The Twins were the ultimate softies, supposedly. In the dugout before tonight's game Rich Dauer was chuckling over Minnesota's misfortunes. "Twenty-seven losses already," he said, shaking his head. "That's hard to believe."

With tonight's loss, the Orioles have 20 failures themselves.

"The main problem of this team is simple. We usually give up one more run than we get," said Palmer, who complained after the game that an out-of-line vertebra was giving him problems on the mound. He also he said he did not mention his pain to anyone while he was pitching. Perhaps, offered one wag, he wrenched the vertebra watching Brunansky's herculean homer.

Both the Twins and Orioles played tonight without their sluggers. Eddie Murray is limited to pinch running for three or four more games with tendinitis of the wrist and Kent Hrbek of the Twins is likely not to play the remaining two games of this series with a bad hand.