A handful of central and northern Illinois Democrats are urging Gov. Pat Quinn to drop plans to close seven correctional facilities because of overcrowded prisons. Sen. Pat McGuire said yesterday that the youth detention center at Joliet is the only facility for the worst juvenile offenders. The Joliet Democrat says closing it would make the rest of the system more dangerous. McGuire was one of at least five lawmakers or legislative candidates who planned to speak out against Democratic Gov. Pat Quinn's plan. He wants close prisons at Tamms and Dwight, three halfway houses and the Joliet and Murphysboro youth centers. They join a solid southern Illinois Democratic contingent urging the General Assembly to restore funding for the facilities that Quinn vetoed last spring. The Legislature meets next month.