Steve Scott won the 1,500-meter run in 3:35.15, fastest time in the world this year, and Rod Ewaliko took the javelin with a throw of 291 feet today to highlight the final program of the U.S. Olympic track and field trials.

Scott, ranked No. 3 in the world last year, took the lead after the first lap and led the rest of the way while posting the second fastest time of his career. Steve Lacy was second in 3:36.73, his best time ever, and Mike Durkin was third in 3:38.04.

Don Paige, who won the 800 earlier in the trials, quit the 1,500 with a lap to go. Last year, he won both the 800 and 1,500 at the NCAA championships but this year ran only in the shorter race and won it.

Former Oregon standout Matt Centrowitz overtook Dick Buerkle and Oregon junior Bill McChesney on the final lap anbd pounded to victory in the 5,000 in 13:30.62.

In the other finals, Benn Fields won the high jump at 7-5: American national champion Lorna Griffin took the women's discus at 197-6, a trials record, and Mary Decker took the 1,500 in 4:04.91, an Olympic trials record. r

Ewaliko threw the javelin further than any other U.S. athlete this year but runner-up Bruce Kennedy seems to have been the record-setter.

Ewaliko's throw made him no. 2 perfomer in the world this year. Ferenc Paragi of Hungary set the world record earlier this year at 317-4.

Kennedy's distinction brought only tears. He threw the javelin 274-5 to qualify for the third straight Olympics in which he can't participate.

"I guess it's a world record," he said. Kennedy made the Rhodesian Olympic teams in 1972 and '76. The '72 team was sent home from Munich because of Rhodesian racial policies. The '76 likewise was barred from Montreal.

In 1977 Kennedy became a U.S. citizen with Olympic aspirations. Today he qualified to miss the Olympics a third straight time, although Rhodesia, now called Zimbabwe, will complete in Moscow.

"That's the ultimate irony, " Kenndey said. "But I'm an American and I intend to compete for America. did it because I own property here, I live here and I have an American wife."

Kennedy, 29, plans to go to Zimbabwe in three weeks to visit his parents, whom he hasn't seen in four years. "It's a great country, politics aside," he said. "It's one of the few countries in Africa making a transition."

He plans to try to qualify for the 1984 Olympics.

Ewaliko, 26, is a 1976 graduate of the University of Washington. His previous best throw was 288-10 in Russia in 1977.

His goal, he said, is the U.S. mark of 300 even, set in 1970 by Mark Murro.

Duncan Atwood, a teammate of Ewaliko at Athletic West, finished third today at 271-3. Tom Petranoff matched that but Atwood had a better second throw.

In two women's non-Olympic events, Ester Mahr won the 400-meter hurdles in 57.46 and Julie Shea took the 5,000-meter run in 15:44.12. Shea won the 3,000 steeplechase, 5,000 and 10,000 at this year's collegiate championships, a feat regarded as one of the all-time greatest by an American.