A third of a million people are waiting for the Indiana sunrise, poised for the speedway to open at 5 a.m. today so they can claim squatters' rights for one of the most nervously awaited of all Indy 500s.

The usual high-octane blend of spectacle and speed has been boosted with speculation about unusual race strategy and perhaps unparalleled risk. The Brickyard is buzzing as fans have joined racers in their anticipation of a uniquely thin "ragged edge."

Never have the Indy cars gone so fast - averaging more than 192 miles per hour for the entire field in qualifying on a 2 1/2-mile oval track that was built in 1909 for cars going 75 miles an hour.

never have all three front-row drivers - Tom Sneva, Danny (The Hurryin' Hawaiian) Ongais, and Rick Mears - qualified at over 200 miles per hour. And never has a front row had so little combined Indy experience - five races.

Never before has the second row been filled with former Indy champions - Johnny Rutherford ('74 and '76), Al Unser ('70) and Gordon Johncock ('73).

Never before have three of the biggest names in the field - A. J. Foyt, Bobby Unser and Mario Andretti - been so far back in the field with so much ground to gain.

"Seven come eleven," the bettors are saying here, since ol' A. J., the four-time champ, and Bobby U, are in Row Seven at the start and Andretti is the last man in Row 11.

Seldom have the prerace intimations of "problems," as Indy Euphemistically calls deaths, been so clearly spelled out by the normally stoic drivers themselves:

Speed-curbing sanctions slowed down the Indy field after three deaths at the 1973 race. Now, however, engine-uity has finessed the new restrictions and speeds have passed the '73 level.

Racers like Bobby Unser claim that the prime racing "groove" is narrower than ever, that the track outside the groove seems slick, and that the margin for error in the corners in infinitesimal.

Never have three chargers like Foyt, Bobby Unser and Andretti started behind so many Indy rookies (five) who are so much slower.

"There's gonna by a freight train leaving when that green flag drops gonna be on it," predicted one crew and A.J., Bobby and Mario are sure chief.

"If one of'em sees a hole down low, he'll go for it and the others will follow. hyed' try to pass the world on the inside before they hite the first turn if they can. Those rookies are gonna have a fearsome sight in their rearview mirrors."

Temperatures may approach 90 with a threat of rain the afternoon. The heat (only two Indys have been run in temperatures over 90 degrees) causes tire wear, more pit stops, driver exhaustion and boiling engines blowing into the Hoosier sky.

Drivers without great cars may be tempted to boost their engines early, ignore fuel consumption and gamble that rain will cut short the race while they are still near the front. More risk.

None of these factors is overwhelming, but look at the number of them. Even pole-sitter Sneva, second to Foyt last year, said, "We're going 20 miles an hour too fast. But you won't see drastic changes until you have drastic problems."

If awareness of danger is any part of the solution, than this Brickyard is up to its eyeballs in safety consciousness. Nearly every driver reiterates that "a 500-mile race is never won on the first lap."

Nevertheless, there are three worrisome exceptions to this caution chorus. While the Rutherfords and Johncocks call for speed cuts, Foyt sneers and says, "Speed records are made to be broken." Bobby Unser says, "I can't think about slower; faster is my concern . . . You're only cheating in auto racing if you get caught." And Andretti adds, "It won't take me long to get near the front. The danger of the first couple of laps is my only concern."

Many drivers anticipate a war of attrition. On the last 90-degree Memorial Day (1953), only a dozen cars finished and one driver died of heat prostration.

In addition to worn tires, blown engines, rookies and the inevitable wrecks (never an Indy without one), there are 10 of the spectacular but skitterish new Cosworth engines in this 33-car field.

While the high-powered Penske-Cosworth team of Sneva, Andretti and Mears, all 200 mph qualifying cars, worry about their experimental engines. Foyt is already losing hair his grumbling old one. He shipped his power plant round trip to Houston in the last two days for repairs.

All these ominous discussions do not hurt the type for this event, which Andretti calls "the greatest anywhere in the world for any kind of racing. No one disputes it."

Many moments of silence have already have been observed here this weekend - Tony Hulman, for deceased Speedway president, and for seven USAC officials killed in an April plane crash.

Nevertheless, a touch of genuine sadness, a bit of morbid fascination, does not harm to the Indy 500.

This is far from a normal sports event. You don't draw 350,000 paying customers - the largest gate for any sports event - by offering a sedate final score and a loving cup.

The pull of the 500 has many tentacles and is almost universal. At the visceral level, Indy's lure is as simple as speed, luck and death.

"About half the people here have come to see someone get killed," said Rutherford's chief mechanic, Steve Roby.

"I've seen 26 of my friends killed while driving," Foyt said here off-handedly. The Indianapolis News prints the names of every driver, fan and pit crewman killed in the first 61 races. It averages out to exactly one a year.

On the other hand, Indy-type car racing is as complex as any buff could want. Janet Guthrie and Tom Bagley have degrees in phsyics. The glistening, sleek beauty of the cars, the note of fear in the turbocharger's whine and the arcane mysteries of the mechanics go hand in hand.

Indy has a seine to snag any sort of fish. For those who demand a grand and historic setting, the Speedway exceeds its reputation. The almost mile-long green grandstand opposite the pits is like a dozen huge old ballparks strung end-to-end.

No football or baseball stadium has a fraction of the dimension of the Speedway.You could drop Santa Anita, Yankee Stadium and the Astrodome inside the Indianapolis infield and seemingly lose them in its 539 acres. Fans have come to Indy for years and never noticed the nine-hole golf course in there.

The Super Bowl builds for two weeks and fans get jaded. The racers have been at Indy for a solid month and the buffs can't get enough. Last week's qualifying trails drew 175,000. An off day when nothing is scheduled will attract tens of thousands to view the motionless cars.

Yesterday, Indy held its annual public drivers meeting. The 33 heroes sat in an old bleacher for 30 minutes and listened to a few harmless mumbled instructions and some praise.

For this chance to see the Indy Field gathered in one living group portrait, the Speedways has to send out 5,000 engraved invitations.

That bleacher full of racing courage would make a strange oil painting for posterity. "Who were these people that hundreds of thousands traveled to see?" the caption might read.

It would be impossible to guess. Some, like George (Ziggy) Snider, are 40 pounds overweight. Others, like Andretti, are short (5-foot-6).One is a 6-foot-tall woman, Guthrie, in silver reflector sunglasses.

The lean Mears and the mesomorph Foyt have the same unblinking look. Several of the 33 are over 40 years old, and some are gray-haired and look as though they were 50ish salesmen.

As the crowd fell silent, a Catholic priest came forward in black shirt and Roman collar. As he prayed, two Nikon cameras swung around his neck and a black ARCO Graphic racing hat sat squarely on his head.

A few feet away in the crowd was Miss Hurst Golden Shifter, "The lovely Linda Vaughn," with her 42-inch bust and paint-on black costume.

If mid-America has a hardhat Woodstock, this is it. This is a fancy undress ball, a low-fashion parade.

Paris designers now stamp their brand names on their "signature-original" clothes. But they stole the idea from the auto-racing tracks.

"Sugar Ripe Prune Special," says one of a thousand varieties of T-shirt embalzoned with Indy car names. There seems to be a different hat for every head, ranging from your basic Norton team hat to straw cowboy 10-gallon jobs that blend well with full beards.

For the racers themselves, this bash is a three-day celebration of their racing roots. Six of the Indy 500 race drivers were careening around the Fairgrounds track at 130 m.p.h. in Friday's sprint-car races. Others watched.

"I just love driving," said rookie Indy driver Joe Saldana. "It's a good thing that they have a rule that says nobody in the 500 can race on Saturday night. There's a bunch of us, and Super Tex (Foyt) is one of us, who'd probably run the sprints on the dirt on Friday, do the midgets in the Little Indy on Saturday night, then get up with red eyes for the 500 on Sunday morning."

As gradually as the 500 puffs itself up to maximum inflation for the eardrum shattering stampede that follows, "Gentlemen, start your engines," that is just how fast this town deflates after the checkered flat falls.

On Indiana state trooper recalled an alarm at 10 o'clock Sunday night after last year's race.

"Nothing much," explained the trooper. "Just some fellow sitting' on his front porch, shooting his rifle at the Goodyear blimp."