The Indianapolis 500-mile auto race, America's largest single-day sports attendance attraction, is to get under way at noon Sunday (EDT) with possible record heat threatening to change the character of event.

Some 350,000 spectators are expected at the Indianaplois Speedway to witness the race, which will be televised on a delayed basis (9 p.m., WMAL-TV-7). The race will be carried live on radio, WPOC-FM-90.

Weather Bureau officials said the temperature was likely to reach 92 or higher.

The highest previous temperature in the 60 runnings of the racing classic was 91 degrees, attained in 1919, 1937, 1942 and 1953.

In the 1953 race, held on a day described as the "hottest race day in 20 years," the temperature on the then-all-brick surface reached 130 degrees. There were 15 relief drivers in the race, most of them getting into the cockpits because the starting drivers could go no further in the heat. Only 12 of the 33 starting cars were running when the winner crossed the finish line.

Driver Carl Scarborough died from heat prostration two hours after he was lifted from the cockpit unconscious.

The temperature on the new asphalt surface of the track could reach 150 degrees during the race. In 1975, when the temperature reached 85 degrees, the track temperature reached 150 degrees.

The heat on the racing surface might contribute to a record number of pit stops for tire changes. It's likely the cars my have to stop about every 25 laps anyhow to take on fuel since they are limited to 40-gallon tanks and are expected to average about 1.8 miles per gallon.

But it is likely they also will change tires on every pit stop since the excessive heat causes the tires to soften and lose their conformation at racing speed.

There appears no chance that rain, which has halted the race short of its scheduled 200 laps three times in the last four years, would force a quick conclusion Sunday.

As many as a dozen drivers are considered capable of winning the 200-lap holiday grind.

A half-dozen former winners are among the favorites and Janet Guthrie, first women to qualify for racing's richest event, is one of seven rookies in the lineup.

The drivers were told they could warm up their engines twice before th flying start of the race at noon - first in the pits and then when they are lined up in 11 rows, three abreast on the race track.

Among the favorites are defending champion Johnny Rutherford, A.J. Foyt, brothers Bobby and Al Unser, Gordon Johncock and Mario Andretti's teammate who smashed the qualifying records two weeks ago.

Others to be reckoned with include Wally Dallenbach, winner of the recent Trenton 200, Pancho Carter and Bill Vukovich in Foyt's backup machine.

They will be shooting for the race record of nearly 163 miles per hour by the late Mark Donohue five years ago.

Most of the favorites start up front, but Rutherford must challenge for the lead from the 17th position. Although a miscalculation cost him the chance to qualify on the opening day of the time trials, he turned in the third best speed.

Because of the lingering heat, most drivers indicated they planned little in the way of strategy.

"I hope to run all day and stay out of trouble," said Foyt, a three-time winner. I'll try to go as fast as I can. If I can get the lead on the first lap, I'll take it."

Foyt starts from the inside of the second row with Johncock in the middle and Andretti on the outside.

The two Unsers, both winners twice, will join Sneva in the first row.

Guthrie, a last-day qualifier, will start in 26th position.

"My chances for winning are slim," she conceded, "but hope to turn in a consistent performance.

Hot weather may slow the pace, but the leaders could bolt from the starting line at high speeds until the field is strung out.

But, nobody can go at full throttle for any length of time without risking the possibility of running out of fuel. Each car is allowed 280 gallons.

"The drivers are going to hav to hold speeds down in the 180 M.P.H. bracket if they hope to have enough fuel to finish the race," said chief steward Tom Binford.

Among the other rookies in the lineup are Swiss Formula I veteran Clay Regazzoni and Hawaiian-born Danny Ongais.