Tuesday through Thursday, 4 p.m. till 2 a.m.; Friday till 3 a.m.; Saturday, noon till 3 a.m., Sunday till 2 a.m. Closed Mondays. Major credit cards accepted. Reservations for large parties advised. Persons in wheelchairs welcome. Jam session held Sunday afternoons-all groups andindividuals invited to play.

A wooden billboard stuck on top of an old Ford pick-up truck parked at the corner of Lewis Spring and Old Branch Avenues in Clinton points the way to Sam's Crab House - and some of the tastiest steamed hardshells in town.

Sam's is nestled in a large parking lot and built in the great tradition of roadside taverns, a one-story cinderblock and plywood structure whose lines are unbroken by achitectural geegaws like windows. Actually, Sam's used to be Weisman's smoked fish company and was converted to a restaurant in 1966.

Inside, Sam's is cool and dark, the walls filled with old advertising symbols and slogans, ancient cannonballs, displays of sailor knots and life preservers from ships sunk or mothballed long ago (one preserver is from the A. J. Cermak, named for the man who, trivia buffs might remember, was mayor of Chicago during FDR'ss time).

At one end of the long dining area, red globe lights illuminate the dance floor which is presided over by a rock band six nights weekly. To the left is the game (pinball) room and to the right is the bar.

This may not sound like a family restaurant, but it is. The night we went there babies slept in infant carriers while their parents ate, middle-aged couples danced to "The Great Pretender" and teen-aged girls in tiny shorts frequently went to the ladies' room to repair their eye shadow. Children are a natural part of the scene and nobody seems to mind them wandering around between courses.

Our group - five adults, our 10-year-old daughter and her friend - sat at a table draped in brown paper. The menus came in plastic baggies to save them from tartar sauce and melted butter.

We were intrigued by a drink called "White Lightening," which came in a "free Bicentennial Mason jar," and wondered at the consequences of a "32 oz. Zombie," but settled for beer on tap.

Crabs came in four sizes - small, ($5 a dozen), medium ($7), large ($10) and jumbo ($13). We went for broke and ordered jumbo.

As starters we decided to have steamed cherrystones ($3.50 a dozen) and two people asked for crab soup and shrimp cocktail. Somehow the crabs arrived first, but in this type of free-for-all meal, it didn't really matter.

Sam Hibib, the owner has devised a fine crab seasoning that has plenty of zest but doesn't set you on fire. It includes rock salt, red pepper and other spices that he refuses to name, and extra seasoning is available for masochists. The crabs were sweet and most were cooked to the proper point.

The shrimp cocktail, which is hard to mess up, and the crab soup earned high points, as did the accompanying cole slaw and onion rings fried in a tempura-like batter. The steamed clams were quite salty and many were too large.

After a couple of hours, our waitress rolled up the brown paper and reeled off the dessert list. The Strawberry Square, a whipped cream concoction on a bed of walnuts, and grasshopper pie with creme de menthe - both made lavishly by Patricia Habib, wife of Sam - are not to be missed.

While the rest of us drank coffee, the girls fed quarters to the pinball machines and hung around the edges of the dane floor watching people jitterbug ("weird," they said). The band had started playing at seven and was so loud the bottle of vinegar on our table was shaking, but requests to cut the sound back were honored.

We finally took a few spins around the dance floor to "Secret Love" before settling the bill - $33.70 for two adults and two children.