For more than four decades, Mayors of New York City have announced drives to clean up the area. And a renewal plan announced last month calls for the restoration and conversion of theaters on the block and the construction of office towers, an apparel mart and a hotel or apartment building.

Until now, the street has been an ignored no man's land between the theater district to the north, the garment district to the south, offices to the east and the Clinton neighborhoods to the west. Planners hope the renewal project will bring these groups together to change the street, but those whose way of life would be changed are doubtful. Only the Faces Change

''The street never changes,'' said Charles Jones, an I.B.M. keypunch supervisor who grew up in Huntington, L.I., and still returns to 42d Street for the excitement. ''The faces change -some end up in jail or dead - and they have police sweeps to get everyone off the block, but nothing changes.''

West 42d Street between Seventh and Eighth Avenues is one of the most traveled streets in the city, with nearly 8,000 pedestrians counted in an hour in one study. It is also the most patrolled block in Manhattan and, according to Mr. Weisbrod, the worst for crime.

Sixteen uniformed officers patrol the street on foot in the evening hours, along with mounted officers and anticrime officers in street clothes.

But during the evening hours in the 10-block area surrounding the street, there were 1,107 felonies committed in the first five months of this year -mostly robberies and grand larceny cases - and 464 arrests for felonies and 532 for misdemeanors.

Police officials say the officers can keep large groups moving and issue summonses to those who refuse to obey, but they can do little else about what one police captain called ''street pollution.'' They, too, feel helpless in trying to change the street, short of rebuilding it or knocking it down.