The big guy with the bad luck, Buddy Baker, won today's Daytona 500 stock car race at an average speed of 177.602 miles per hour, making this the fastest 500 miles ever raced.

In 18 years of trying, in 34 races on the Daytona International Speedway, Baker had never won here. He lost once when a tire went flat with three laps to go. He had his game's most prestigious prize in his hand five or six times, only to see it slip away.

"I'd been close enough before to think about how I had to mention all the manufacturers in my victory lane speech and not leave any out." Baker said today. "With about 10 laps to go today, I started thinking that way and I said, "Don't even do that!"

Thanks to a daring gamble on his pit stop with 19 laps to go on the 2 1/2-mile trioval, Baker's finished the $660,500 race about a half-lap ahead of Bobby Allison and a full lap in front of Neil Bonnett.

Baker's pit stop was accomplished in six seconds, less than half the time Allison needed and 19 seconds quicker than Dale Earnhardt, who dropped from second to fourth when his crew sent him into 190 mph traffic with a loose lug nut.

While the other races took on two 11-gallon cans of fuel and/or changed two tires, Baker's crew chief, Waddell Wilson, decided to go on with one can of fuel and the old tires.

A can of fuel is good for 18 laps here for these 700-horsepower thunderstorms on wheels. Wilson's gamble was that Baker's Oldsmobile still had a few drips of fuel left from the last fillup, enough to make it that one more lap necessary to win.

By then, only a stroke of the meanest misfortune could have beaten Baker. He had vanquished his principal competitors: Donnie Allison seventh place) was never in the hunt, Cale Yarborough (19) fell out after a fourth-turn collision knocked his engine silly; Richard Petty (25th) had clutch problems; A. J. Foyt (31st) developed a vibration in his Olds that nearly threw him overboard, and Darrell Waltrip (40th of 42) ran only 20 laps before putting his slick engine to bed.

Which is not to say Baker could not have lost this race. Though he has won more this race. Though he has won more than $1.7 million in 21 seasons, he has lost races in unusual fashion, including the 1969 Texas 400 when, with a two-lap lead, he crashed on a caution lap. Because it is the 6-foot-5 strongman's bent to race flat out from dawn to dusk, his cars sometimes rebel. They break.

"Give Buddy an anvil for breakfast, he'll break it by lunch," a critic once said.

So Baker, on that one can of fuel, that one gambling can, did not practice his victory lane speech at the wheel today.

He watched the fuel engine.

The time he crashed in Texas on the caution lap, Baker was looking at his pit crew's signs board, which read, You got it make." Right then, he crammed into the rear end of a car in front of him and tore up his radiator.

"I've done some stupid things," he admits.

A certain sinking feeling came over him today, too, when he looked at that fuel gauge and saw two pounds of fuel pressure.

"That's the same," he said, "as when you're in your road car going down the interstate and it starts to jumping because it's getting air instead of fuel.

"With two laps to go, it fell to two pounds and I thought. "Oh, no, I know what's going to happen now. I'm goint to coast to the start-finish line and not cross it."

Instead came the kindest help, for ust as Baker might have thought about asking someone in the crowd of 100,000 for directions to a gas station, the yellow caution light came on because John Utsman's Chevrolet had blown an engine.

That effectively won the race for Baker because now, on the last lap, the 39-year-old North Carolinian' could coast home at half-speed if need be. The race ended under yellow.

With or without the last-lap help, with or without the pit-stop gamble, Baker's victory seemed inevitable today. His Olds was "a superior race car, just perfect. . . all I had to do was keep it between the walls. It did everything I wanted it to do. I ran high in the turns, low in the turns, down the center, everywhere.I'm 90-percent sure there wasn't another car on the race track even close to ours."

With only five caution flags for 17 laps on a day when no racer was injured, Baker led 143 of the 200 laps to set the 500-mile speed record. The previous fastest 500-miler was 174.700 at Talladega, Ala, by Lennie Pond. The Indianapolis 500 record is 162.962 by Mark Donohue in 1972.

Baker's purse today was $60,800. For his week's qualifying and racing work here, he earned $102,275.