Their fans call them an institution, a cultural treasure. The critics shake their heads in wonderment over the group's long track record and its artistry.

The Dixie Hummingbirds, who've been singing gospel for 50 years, say they're just doing the Lord's work.

"Lots of our friends have written us off as being washed up," laughs James Davis, 62, who founded the group 50 years ago as a lad in Greenville, S. C. "But we just keep going. The Lord has something else for us to do."

He spoke Saturday night at a Harambee House dinner paying tribute to the Hummingbirds' 50 years of singing. The $15-a-plate event, attended by about 325 people, was organized by the Washington chapter of the Dixie Hummingbirds Fan Club.

Calvin Rolark, president of the United Black Fund and publisher of The Washington Informer, recalled that as a youngster in Texarkana, Tex., he idolized the Hummingbirds.

"I was a member of the Goodwill Baptist Convention and we used to look forward to seeing the Hummingbirds because they had no peers," explains Rolark.

Bill Solomon, president of the fan club, said the organization was established in 1977 because "a group of us would always go together to the Birds' concerts and we'd sit right up front. So we decided to form a fan club. It's the only one in the country. Some of us have been following the Birds for more than 30 years."

In their time the Hummingbirds have been the most influential gospel quartert. They can wail in sorrowful fashion, preach in loping funky style and shout flamboyantly like the new quarterts.

"When we first started, we sang a lot of sweet songs," remembered Davis. "We just tried to blend our voices. But it got so to get people's attention we had to stomp and shout.

"Yuck (Ira Tucker Sr., the group's lead singer) really started a lot of the rock 'n' roll styles. He started shouting and all those fellows copied him."

Jackie Wilson, Brook Benton and Bobby Bland were all affected by the Tucker style, which ranges from a down home rancous intensity to a soft, moaning fervor.

After members of the group were given plaques the other night, the audience pleaded for a song.

"We don't sing a capella much these days," said Davis. "We got out of practice when our guitarist, Howard Carroll, joined the group 27 years ago."

Still, the Hummingbirds delivered a ringing version of an old hymn, "Beaming from Heaven." They confirmed Davis' assertion that "we're as good today as we were 30 years ago."

The Hummingbirds, rich in tone colors and delicate shadings like the bird whose name they carry, still travel much of the year. Davis is the only original group member left. Tucker has been with the quartet since 1939. James Walkers, the newest member, joined in 1953.

ABC-TV just completed a documentary on the group that will be shown Dec. 18. Paul Simon picked them to back him on his recording of "Loves Me Like a Rock." The Birds won a grammy for their own recording of the song. Recently, Greenwood, S.C., gave the group a day "Everything seems to be going our way," says Davis. "We just keeping rolling on." tr add five-hummingbirds

What's their secret for longevity?

Davis say it's their basic rules and strong religious convictions. They enforce a $15-a-day fine for tardiness and a $500 fine if anyone is caught drinking liquor.

Davis, who says he's never taken a drink in his life, has been anti-liquor since his youth. As a 10-year-old he rehearsed with a counsin's gospel group. One of the members got drunk and brought punishment on the whole group.

"I swore then to have a group and to have a rule against drinking," explains Davis.

The leader recalls the group being stranded by a flood in Texarkana, Ark. "I wanted to play a religious song on the juke box, but I mispunched and up came a Muddy Waters blues tune," he says."I got fined $20 - and $20 was like $500 to us then."

What's the future for the group?

"Hard singing," says Tucker.

"We'd like to sing another 50 years and hang it up," smiles Davis. CAPTION: Picture, From left, Ira Tucker Sr., James Davis, Thompson and James Walker, by Kenneth [WORD ILLEGIBLE] for The Washington Post