The Washington area's delegates to the Democratic National Convention took their first bites into the Big Apple today, and many found it tough to swallow.

A predawn train from the nation's capital was overbooked, and another, destined for Manhattan, arrived in Newark instead. Beer costs more than $2 a bottle, hamburgers at least $6 apiece and one delegate complained that chewing gum costs twice as much here as it does in Joppa.

They found thousands of demonstrators in the streets over here, hundreds of burly police lined up three and four deep over there. Taxicabs couldn't get to the hotels, and delegates' family members couldn't get guest floor passes to the convention -- even with a Georgia connection.

The only clear winners in the battle against New York were the Baltimore Orioles, who beat the hometown Yankees, 6-5, on a sunny Sunday afternoon in the Bronx.

But even that victory was soured for Montgomery County Executive Charles W. Gilchrist and Baltimore County Executive Donald Hutchinson who spent the afternoon at Yankee Stadium instead of politicking.

"I was really disappointed because we had to leave during the eighth inning in order to make the Maryland delegation caucus," Gilchrist complained. The Orioles' exciting come-from-behind victory came on two runs in the ninth.

A visitor, impressed with the wicker chairs, smoked glass coffee table and thick carpets of Mayor Marion Barry's two-bedroom suite on the 14th floor of the otherwise underwhelming Roosevelt Hotel, complimented the mayor on how nice his quarters were.

"It ought to be nice, It's costing me nearly $1,000," groaned Barry, who brought his wife, mother and young baby son along.

Most of the 142 delegates from Maryland, Virginia and the District of Columbia rejected the once traditional practice of piling into a Fried Chicken Express and riding to the convention together, cutting deals in smoke-filled club cars along the way.

Many of the delegates flew to this convention, and several who came together must have known that misery loves company.

One contingent from Richmond began the journey north at 4 a.m. aboard an Amtrak train that was overbooked. Many of them wound up standing for part of the trip in a club car that was not air conditioned.

Others from the Old Dominion arrived here in the midst of a huge counter-convention demonstration that snarled traffic and virtually halted all mid-town movement. "I had to lug my luggage four blocks to my hotel," complained one disgruntled delegate.

Fifteen D.C. delegates and some from Maryland found their train detoured from Penn Station in midtown Manhattan to Newark, in order to avoid demonstrators. The delegates were bused into New York.

The inconvenience didn't stop State Sen. Edward T. Conroy of Bowie, the Democratic nominee running for the Senate seat now held by Sen. Charles McC. Mathias, from touring up and down the train and lobbying the delegates for votes and money.

"I'm not a Heinz," Conroy told one delegate, referring to John Heinz, the junior senator from Pennsylvania and the richest man in the Senate. "To run for senator now," Conroy said, "you've either got to sell out to every special interest in America or be a millionaire."

The cost of life in convention city is a major headache for many in the delegations.

The Roosevelt Hotel, headquarters of the D.C. delegation, has faded carpets lining the hallways and patches of crumbling plaster disfiguring the walls. But it is charging $61 for single rooms and $72 for the cheapest doubles.

"I couldn't afford it," said D.C. City Council member David A. Clarke, a Kennedy delegate. "I'm staying with a friend of a friend, I'm eating at cheap steak houses and I'm taking the subway." Clarke said he has had only one meal since he arrived Saturday night.

Council member Betty Ann Kane, another Kennedy delegate, is staying with her mother in Tenafly, N.J. and commuting to the convention.

Delegate Paul G. Yorkis of Joppa, Md., brought along 15 packages of sugarless gum. "If I fed a machine in New York," he said, "gum would cost me a quarter a pack. At home, I got six packs for 89 cents."

Ginny Lehner, a Carter delegate from Fairfax County and a survivor of the 1976 convention here, is another brown-bagger. "I brought three boxes of Figurines, and I'm planning to eat them all," she said. "I found out hamburgers here were $6 and up and that Cokes are $1.65."

Gerald T. McDonough Jr., a Prince George's county councilman and a Kennedy delegate, entered the bar at the Holiday Inn Coliseum, where his delegation is staying, to order his first beer. The price was $2.45 -- $1.75 more than he pays at his favorite hometown watering hole, the Old Towne Inn on Main Street in Upper Marlboro.

"It's really infuriating to get held up like that," McDonough said. "They might as well put a gun to my head. But I had to pay it. I wanted a beer."

The Virginians, housed in the Sheraton City Squire Hotel on the fringes of New York's infamous Hell's Kitchen, have become bosom buddies with the Georgia delegation, which also is staying there. But members of neither delegation have been very successful in getting coveted guest floor passes for the convention.

An aide to Georgia Gov. George Busby told some "there's just no way" they could get passes for Monday night's touted Carter-Kennedy showdown. But, he quickly added, "We're going to try to make sure that everyone who came to New York from Georgia gets to go to Madison Square Garden -- at least once."

The Maryland and Virginia delegations are for Carter, the District, for Kennedy. But much of the internal fighting subsided today as the two major rivals headed toward conciliation.

Rep. Michael D. Barnes, the Montgomery County Democrat who became a spokesman for the now apparently doomed Kennedy-led "open convention" movement, made himself available to discuss the movement with Maryland delegates. But few immediately volunteered to listen. Barnes said his primary concern was that "we come out of here with a united Maryland delegation."

Meanwhile, Peter Messitti of Silver Spring, the lone uncommitted delegate from the East Coast, was being hounded by reporters from all over the country and juggling interviews with television networks. He even received a telephone call, he said, from an old friend -- White House aide Stuart Eizenstat, who said he hoped Messitti would "be with the president."

All three delegations held caucuses today in anticipation of formal convention activities, which begin tomorrow and are expected to proceed firmly under Carter's control.

"Where's the excitement at this convention?" a reporter asked Florence Pendleton, an alternate Carter delegate from the District. "Honey," Pendleton responded, "we brought it with us."