The Jim Dandy Stakes honors the perpetrator of racing's greatest upset, so it probably ws appropriate that an improbable longshot beat some of the country's better 3-year-olds in the event today.

Willow Hour, whose 18-to-1 odds were fully deserved, had a victory handed him by the gods of chance. He defeated the highly regarded West Coast invader Lemhi Gold by half a length and left Belmont Stakes winner Summing far behind him, but the circumstances were even flukier than for Jim Dandy's victory over Gallant Fox here in 1930.

The Saratoga track has been highly favorable for speed horses, but none of the thoroughbreds in this prep race for the Travers Stakes possessed much early speed. After the short run to the first turn, the field was virtually eight abreast.

It was, at leat, until No. 4, Silver Express, made a right-hand turn, smacked into the favorite, Sportin' Life, who in turn bounced into Lemhi Gold. Willow Hour managed to escape most of the damage.

"All the problems were inside me," jockey Maple said. "I dropped back after that some, and waited until it cleared." Then Maple sent Willow Hour up on the outside to challenge Summing for the lead.

The two of them still were dueling for the lead on the far turn when Lemhi Gold and Sportin' Life got back into the picture. Both tried to accelerate and looked as if they might win the $50,000 event, but on this Saratoga track stretch-runners have had trouble gaining even on bad horses. Just as front-running longshot Fio Rito held off the late challenges in Saturday's Whitney Stakes, Willow Hour did it today.

He lasted by a half-length over Lemhi Gold, with Silver Supreme another half-length back in third place and Sportin' Life fourth.

Summing faded to finish last, which jockey Goerge Martens blamed on the weight: "He's such a little horse, and to carry that package (128 pounds) is a bit too much." But Summing's performance, in view of the fact that he escaped all the trouble that befell his chief rivals, was a dismal one.

The winner paid $38.40, $12.40 and $7. Lemhi Gold returned $6.20 and $5, with Silver Supreme paying $6.80.

Willow Hour, who had not won a stakes race this year, covered the mile and one-eighth in 1:49 1/5, poor time over an extrqaordinarily fast track. (Earlier today, an allowance-class sprinter had missed the six-furlong track record by two-fifths of a second.)

Although the Jim Dandy is a prep race for the rich and prestigious Travers two weeks hence, it seems unlikely that the Travers winner was in this field. Certainly, it won't be Willow Hour.