PHILADELPHIA is quiet. Almost too quiet.The local mayor's race has a case of the summer doldrums. The city's financial mess - once a topic of national interest - grinds on in obscurity. This calm is temporary, political and financial experts say. They expect fireworks: first, from a hard-fought mayor's race; then, from some tough budget cuts. "I will be surprised if this year proceeds without crisis," says Dianne Reed, director of the eastern division of the Pennsylvania Economy League. "This [financial problem] is not going to be faced by playing at the margins," adds Ted Hershberg, director of the Center for Greater Philadelphia at the University of Pennsylvania. These two explosive issues - political change and fiscal reform - are linked. Many Philadelphians say their city has to accomplish both very soon if it is to avoid disaster. Philadelphia has sidestepped disaster so far. After nearly running out of money last winter, the city allowed the governor and state legislative leaders to appoint a fiscal oversight board, the Intergovernmental Cooperation Authority. The five-member authority must approve the city's spending plans. If it does, it can sell bonds so that Philadelphia can cover its immediate deficits. That's terrible fiscal policy, Ms. Reed says, but it is politically convenient. Most observers here believe fiscal reform won't come before a new mayor and City Council are installed. The current mayor, W. Wilson Goode, and City Council are too discredited to accomplish much, they say. Philadelphians face a stark choice for mayor: Democrat Ed Rendell, a former district attorney, and Republican Frank Rizzo, the city's colorful former mayor and former police ommissioner. Mr. Rendell is the heavy favorite to win in November. He finished with a strong 49 percent of the primary vote even though he faced three well-known opponents. (Mr. Goode did not run; Philadelphia limits mayors to two terms.) Rendell proposes some sweeping reforms. The most politically sensitive is privatizing city services. Private firms would compete with municipal unions to provide services at a low cost. "This is a city whose workers get Flag Day off - Flag Day! Give me a break," says one local businessman confidentially. "The business people in this city would be willing to put up with a long, violent strike to get control" of the costs of the municipal payroll. Mr. Rizzo is running on his law-and-order reputation. He proposes to increase the police force by 1,500. (Rendell proposes an increase of 1,000 police.) Rizzo opposes privatization and says he won't have to cut employees from the city payroll. "It was a good town," he says. "While we were away, it fell apart. We are not going to cut anything. We are going to rearrange the money." Most observers don't give Rizzo much chance of winning back his old post. Any Republican has a notoriously tough time getting elected in this Democratic city. And Rizzo's high negative ratings make it doubly hard. "The numbers aren't there" for a Rizzo victory, says Mr. Hershberg of the University of Pennsylvania. But Rizzo has snatched victory from defeat before, most recently in the three-way Republican primary in which he defeated a popular district attorney by a razor-thin margin. The odds against victory are even bigger this time, but many observers hesitate to write Rizzo off. The key is the black community. In the primary, Rendell polled nearly 20 percent of black voted despite the presence of two black candidates. Many black leaders criticized the heavy-handed tactics of Rizzo's police force in the 1960s and '70s. On the other hand, Rizzo is reaching out to the black community. His strong stand on law and order is especially appealing to inner-city blacks, surrounded as they are by a culture of crime and drugs. Conceivably, Philadelphia's new mayor can handle the city's structural deficit, estimated at $219 million this fiscal year and, if costs remain level, $42 million in the next fiscal year. But, according to businessmen, politicians, and financial experts within the city, Philadelphia can't go it alone for very long. It will need state aid within the next few years to cover the rapidly escalating costs of social services to the homeless, AIDS patients, crack babies, and others. "If you take the city and run it well, there is still a burden of social services where there isn't enough money," says David Brenner, Philadelphia's finance director. The next mayor will have to convince state legislators the city is no longer wasting money. Then "you are going to see an interesting debate," Mr. Brenner says.