In the vast sea of loyal, enthusiastic Republicans that Ronald Reagan will face when he accepts his party's presidential nomination in Detroit, few will be more loyal -- or enthusiastic -- than those of the Virginia delegation.

Hard-core Reaganites, many of whom have supported the former California governor for the presidency since he first appeared on the national political scene in 1966, dominate the 51-member delegation drawn from one of the nation's most conservative states.

Even the Virginia delegates who in the past were not identified with Reagan, such as Gov. John N. Dalton and U.S. Sen. John W. Warner, eagerly boarded the candidate's bandwagon. Warner, who embarrassed Reagan in 1978 by prematurely endorsing Gerald Ford for president a few days before Reagan came to campaign for Warner, even won an appointment to Reagan's group of congressional advisers on foreign policy and defense matters.

Part of the loyalty stems from the philosophical compatibility between Reagan and Virginia Republicans, who by and large see eye-to-eye on issues like defense spending, foreign policy, abortion and the Equal Rights Amendment. The ERA has gone down to defeat in the Virginia General Assembly for eight straight years, thanks in part to the opposition of Dalton and GOP conservatives.

And the other part of Reagan's attractiveness is that Virginia Republicans smell a chance for a big victory in November and are preaching party unity in an effort to win.

"Everyone is thinking about only one thing -- and that's defeating Jimmy Carter and electing Ronald Reagan," says John Alderson, Reagan's Virginia coordinator.

A glance at the Northern Virginia delegation shows just how solid and longstanding Reagan's support here is. The three delegates representing the 10th Congressional District are Jade West, Reagan's Arlington County coordinator who served as a Reagan delegate in 1976; Naomi Zeavin, also a 1976 Reagan delegate; and Patsy Drain, who in 1976 was Reagan's Fairfax County coordinator. Also attending, as an at-large delegate, is West's who was Reagan's 10th District Co-husband, Raymond LaJeunesse Jr., ordinator.

"There are no new faces in this groups," says West. "We've all been behind Ronald Reagan for a long, long time."

Other Northern Virginians going to Detroit include Del. Lawrence Pratt of Fairfax County, one of the state's most conservative legislators, and former Fairfax Del. Guy Farley, considered a prospective candidate for lieutenant governor next year. Both men are ardent Reaganites and considered members of the evangelical New Right.

Almost all of the delegates oppose the ERA and will support an effort to exclude mention of the amendment in the party's national platform. A majority is believed to favor conservative U.S. Rep. Jack Kemp for vice president, although George Bush is said to have strong support from state party leaders.

"Ideologically I'm for Kemp but pragmatically I think Bush is the better choice," says GOP State Chairman Alfred B. Cramer.

The candidate who could most threaten the delegation's unity is Sen. Howard Baker, whom many conservatives dislike because of his proabortion funding and Panama Canal treaty votes. "(U.S. Sen. Richard) Schweiker, (Reagan's 1976 running mate choice) just split the dickens out of the Virginia delegation," says Cramer. "Baker is the only one that could possibly have the same impact this time."

Only one bona fide former George Bush supporter will be in the Virginia delegation -- former state Sen. FitzGerald Bemiss, a Richmond business consultant. To make room for Bemiss on the at-large slate, the Reagan forces agreed to scrap former U.S. Sen. William Scott of Fairfax, a longtime Reaganite. That trade-off, hammered out in late-night negotiations during the state convention last month, signaled to party moderates that the Reaganites were willing to compromise with them.

The result has been such an unusual degree of GOP harmony that former Gov. Mills E. Godwin, an at-large delegate, announced earlier this week that he planned to skip the convention because his skills as a political compromiser simply were not needed.