Faced with a choice between harmless, expendable juvenile attractions like "The Private Eyes" and "Jacob Two-Two Meets the Hooded Fang," parents would still be better off trusting the first half of "Flash Gordon" and the last half of "Popeye."

A typically poky new Tim Conway-Don Knotts farce, "The Private Eyes," now at area theaters, utilizes the palatial Biltmore Gardens in Asheville, N.C., as a haunted murder mansion. Earlier this year it doubled as the estate of Melvyn Douglas and Shirley MacLaine in "Being There." According to the ground rules favored by Conway and co-writer John Myhers, the setting is supposed to be an English country mansion in the late '40s. The co-stars play an American detective team, a blundering Yankee Holmes-and-Watson called Inspector Winship (Knotts) and Dr. Tart (Conway), who have been inexplicably recruited by Scotland Yard to investigate the deaths of Lord and Lady Morley.

The suspects consist of an heiress, the Morleys' sultry daughter Phyllis (Trisha Noble), and a group of demented servants, notably Bernard Fox as a butler who goes into homicidal rages at the mention of the word "murder" and Grace Zabriskie as a resentful, hollow-cheeked Teutonic governess. While the visiting sleuths snoop around ineptly, getting lost every second or third sequence in secret passageways, fresh victims pile up around them. A ghostly shrouded figure appears to be manipulating events, and the murderer leaves mocking clues pinned to the corpses.

The familiar premise seems serviceable enough to be revived indefinitely, and kids seem content with the movie's low-key, low-energy facetiousness. I can't share the contentment.I wish someone would put Conway and Knotts through their dopey paces at a dramatically accelerated tempo. I've never quite understood the theory behind their partnership, which seems to duplicate the same basic type of second banana: the bumbling, uncomprehending little guy who traditionally requires a big guy -- whose behavior may or may not be equally foolish -- as a foil. At the leisurely tempo imposed by director Lang Elliott, this less than dynamic duo becomes perilously draggy.

Knotts & Conway, first allied by the Disney organization in "The Apple Dumpling Gang," reinforce each other's passivity and twerpiness. The sneaky, puckish side of Conway is evident only in the mildly sick jokes that relieve the prevailing blandness of "The Private Eyes" -- the discovery of a skeleton of Santa stuck inside a remote chimney, for example, or a running gag with Dr. Tart's carrier pigeons, which suffer a 100 percent fatality rate upon takeoff for Scotland Yard.

In the same way that "The Private Eyes" made me curious about reseeing "Ghost Breakers" or "Murder, He Says," the ponderously faithful movie version of Mordecai Richler's children's story, "Jacob Two-Two Meets the Hooded Fang," now playing matinees exclusively at the K-B Janus 2, made me nostalgic for the better movies it echoes every now and then -- Carol Reed's "Oliver!" and "A Kid for Two Farthings" and the semi-notorious musical fantasy "The 5,000 Fingers of Dr. T."

A Canadian-American production made in Montreal in the summer of 1976, "Jacob Two-Two" has had no theatrical exposure to speak of, and it's unlikely to be mistaken for a neglected classic. Despite the occasional splashy costume or elaborate set (there's one vast, impressive underground furnace room where urchins are kept slaving away), the production is compromised by a stilted, amateurish approach.

The Richler book, a first stab at juvenile fiction by a distinguished adult novelist, is a rather tepid and condescending whimsy in which a little boy, the youngest of five children, gets lost while running an errand and dreams of being imprisoned in a remote penal institution for children. The warden, a hulk called the Hooded Fang, is carried over from a professional wrestler the child had glimpsed on television. The expression "two-two" derives from the boy's habit of repeating himself to get attention in competition with his older siblings. In his fantasy he's arbitrarily sentenced by a court of hostile grown-ups for this "offense."

The book has been transposed almost verbatim by the screenwriter-director, Theodore J. Flicker. Indeed, I often had the dismaying impression that I was attending a reading rather than a movie. Since the reading itself is deficient, the stilted aspects are as much verbal as pictorial. All the adult villains are painfully overacted. Flicker seems to have encouraged his cast to perform in the worst tradition of "children's theater," exaggerating every menacing or clownish expression.

Eight-year-old Stephen Rosenberg is an agreeable choice as Jacob, sweet enough to prevent the repetitions from becoming a terrible nuisance anyway, but Alex Karras flails around desperately as the Hooded Fang. The role is conceptually weak: The Hooded Fank ought to be a clever, fantastic embodiment of childish fears, but he's a transparent fraud, a menace easily exposed as a big old softie. Karras' inability to find a performing style for his laughable villain seems to be symbolized by his scrambled, ineffective vocal impersonations -- Slapsie Maxie Rosenbloom gives way to Ed Wynn who gives way to Red Skelton as Clem Kadiddlehopper. gNothing works -- but he's got nothing to work with.

A poor man's "Wizard of Oz," the Richler volume gets a little icky about its allegiance with children. There's a certain smugness about the way the author draws his concluding twittery moral: "Adults who fear children also fear the sun . . . and flowers . . . and pets . . . and laughter." I suspect Richler miscast himself badly in the role of a children's writer. I was confirmed in the impression of my own kids. My 9-year-old daughter declined to go to the movie, having found the book a shrug-off. My 6-year-old daughter tagged along but damned it with faint praise. "Were you scared?" her mother asked, "Are you kidding?" the kid replied.