PORTLAND, Ore. –Three West Coast CBS-TV affiliates said Tuesday they would hold off broadcasting network projections of a winner in the presidential election until around the time the polls close.KOIN-TV, Portland, said it won’t switch to network coverage on Nov. 3 until 7 :30 p.m., a half-hour before polls close. Presumably, anyone who is voting would already be at a polling station or en route to one at that time, said the station’s general manager, Mick Schafbuch. Jim Putney, general manager of KVAL-TV, Eugene, Ore., said his station also won’t pick up the network coverage until 7:30 p.m. And CBS affiliate KXTV, Sacramento, said it would hold off broadcasting the projections until 8 p.m. “I hope the whole West Coast does it,” said its news director, Jan Allen. The major television networks said last week they wouldn’t change their practice of projecting winners based on voter exit surveys that are released as soon as polls close, which along most of the East Coast is by 8 p.m. EST. Critics, including politicians of both parties, say the early projections discourage voting on the West Coast.