The gelding S W Clarence, a dentist's horse with a sweet tooth and a lengthy stride, stood tallest in the $50,000 Hail Emperor Stakes at Laurel Park yesterday.

According to owner and breeder Richard Reveley, the Pennsylvania-bred 5-year-old measures out at more than 18 hands, which is more than 7 1/2 feet. S W Clarence is believed to be the tallest horse racing in the United States.

Conventional track wisdom holds that tall horses have shorter careers, because of the toll the extra bulk takes on their legs and joints. But after erratic, injury-plagued seasons as a 2- and 3-year old, S W Clarence has improved with age. This year was his best yet, having won 6 of 9 starts in the last year.

Reveley traces that improvement to a rather odd discovery made by trainer Thomas Lingenfelter: The horse loves a particular type of hard candy--root beer barrels. S W Clarence's craving for the candy is such, according to Lingenfelter, that he behaves while training just to make sure his supply isn't cut off.

"When this horse was young, I knew he could be good, but he was just too hard for me to handle, and I couldn't ever figure out a way to calm him down," Lingenfelter said. "Well, I had a root beer barrel in my mouth one day, and he was looking at it like he really wanted it, so I gave him one. And I realized that when he has one in his mouth, instead of looking around at other horses, he's so concerned about this piece of candy that he stays calm. He won't worry about anything else except keeping the candy, so I go through several pounds of root beer barrels every week now."

At first, the candy fetish didn't sit well with Reveley, who has a dental practice in Benson, Md. "But I told him, 'Hey, if anything goes wrong with the horse's teeth, you can put him in the seat and fix his cavities, because the root beer barrels are the only thing that calm him down,' " said Lingenfelter.

But by the time S W Clarence won the Norristown Handicap at Philadelphia Park in May--giving Reveley his first stakes win after about 40 years of owning horses--the horse's eating habits were no longer an issue.

Bettors made S W Clarence their fourth choice in the Hail Emperor Stakes, with the Kentucky-bred Montana Dreamin' going off as the favorite. When the gates opened in the 1 3/16 mile trip, jockey Rick Wilson, aboard S W Clarence for the first time, took his mount right to the lead along the rail, and had little trouble staying in front through the final turn. But at the midway point in the stretch, Montana Dreamin' sneaked into first place. S W Clarence, perhaps fearing a loss in this race would put an end to his candy privileges, rallied to retake the lead after only a few paces, and held it to the wire.

S W Clarence finished in 1:56 1/5 seconds--1 2/5 seconds off the track record--and paid $13.80. Montana Dreamin' held on to second.