hey converged here by the carload last week, the long-anonymous state bureaucrats who are to inherit power over billions of federal dollars starting Oct. 1, when the Reagan administration's new budget takes effect.

The occasion was a White House-sponsored conference on block grants to the states, the consolidation of dozens of longstanding federal programs into nine blocks, over which states will have more control. The bureaucrats who came said they expected to learn at last what the federal government will require them to do with their billions.

They were told, in essence, to do as they wish.

"I'm sitting here, and my jaw just keeps dropping and dropping and dropping," said a Maryland official who attended a workshop on the $2.4 billion block grant program for the 50 states and the District of Columbia that covers day care, child abuse programs and other social services. Last year, state officials had to follow 37 pages of federal regulations governing those programs; this year, there will be only two, according to Dorcas R. Hardy, assistant secretary of the Department of Health and Human Services for human development services.

Regulations governing the block grants will not be published in the Federal Register for at least a week, giving the state officials only a few days to study them before the grants go into effect, Hardy said. To state officials who found this cause for concern, Hardy and others insisted that the regulations will be so minimal that state officials will scarcely realize they are there.

"I've been to several regions, and each time I give my talk, people come up to me and ask something like: 'You mean I don't have to publish notices in the front section of the newspaper before we hold a public hearing? I don't believe it!' " Hardy said. "I've had state bureaucrats ask us to put a regulation in the Federal Register saying: 'There will be no federal regulations.' They just don't believe it could be true."

While state officials said they welcome the flexibility that Hardy and others promised, many said they remain troubled that key details of the grants are still unresolved. By Oct. 1, states must notify the federal government which block grant programs they intend to start operating. If they choose, state officials can allow the federal government to control most of the programs for another year, and then take them over in October, 1982.

"It makes it very confusing," said Phil Dearborn, financial counselor to D.C. Mayor Marion Barry. "This is all coming very quickly, and you have to do a lot of quick decision making."

Many state officials looked at each other with alarm during the opening session at the Philadelphia Sheraton auditorium when Hardy announced that the preliminary deadline for states to decide whether to assume control of the community services block grant was Sept. 11--the very day of the briefing.

"That's the first I heard of that," said Ejner Johnson, chief aide to Maryland Gov. Harry Hughes. Hardy added, however, that the states can give notice as late as Oct. 1.

State bureaucrats expressed the most confusion over how the money is to be transferred to their treasuries. "I've asked that question twice, and now I've gotten two different answers," said Rima Bostick, a staff member of the Ways and Means Committee of New York's General Assembly.

In a workshop on the education block grant, state officials complained that most of their questions were answered: "I don't know."

The uncertainty was compounded because the officials don't know how much money they actually will be getting since President Reagan's recent call for further cuts in next year's budget.

Bureaucrats wandered from room to room during the day-long briefing--the fifth of eight being held around the country--learning about grants for health programs, human services, community development, energy assistance and more. And the scenario was generally the same: a federal bureaucrat telling disbelieving state officials that the ball is in their court. "It's a new era," the feds said again and again.

In the social services workshop, for example, HHS's Mike Suzuki told state officials that states will not be required to target a fixed portion of money to the poor, as in the past. Nor will they be bound by the spending plans they submit in advance to HHS since, if they depart from the plans, "You're only violating your own rules," Suzuki said. And once the money is spent, the program will be audited not by the feds, but by an independent auditor appointed by the state, with federal auditors stepping in only in a few cases--for example, if the state audit shows "great problems," he said.

"The anxiety level among these state officials is really high," said Diana Carsey, the District's federal grants administrator. "Everyone keeps asking: 'Aren't you going to be looking over our shoulder?' It's learned behavior that the states probably ought to get over."

But Baltimore's Janet Hoffman said she fears the "new era" will find states paying less attention to the poor. "It's shocking," she said. "Why aren't they telling them to put the money where it can do the best good? They might as well be dealing in peanuts rather than people."

Hardy and others insisted that such fears are unfounded. "We have considerable faith in the states. They feel responsible to their citizens. They want to inform them," Hardy said. And if a state ignores a certain constituency? "The people are the principle enforcers," Hardy said. "These citizens groups know their legislators. The states are going to listen."