Arlington County Board Chairman Stephen H. Detwiler said yesterday he is investigating the possibility of legal action against two board members who disclosed Friday that the board's three-member Republican majority intended to fire County Manager Vernon Ford.

Democrat John Milliken and Democrat-backed Independent Ellen M. Bozman, accusing the GOP officials of "back-room politics," announced Ford's impending dismissal following an executive session Thursday night. At that meeting, Detwiler said he had told Ford on Monday of the majority's decisin to ask for his resignation.

"I cannot express to you how deeply disturbed I am by the press conference that was held," Detwiler said. "And I intend to confer with [County Attorney Charles Flinn] to see if there was and breach of authority." Detwiler said he might call a special meeting to consider Ford's future in the $56,000-a-year manager's job.

Behind this most recent flurry of antagonism between board members and Ford, however, is a long history of political confrontation between county liberals and conservatives. Ford, who took the manager's job in 1976 under a Democratic majority and who oversees the county's $198 million budget and 2,400 employes, had been at odds for years with Detwiler and board members Walter L. Frankland and Dorothy T. Grotos, all Republicans.

Ford's dismissal by only a few months the resignation of embattled schools superintendant Larry Cuban, also a Democratic appointee. The moves culminate what has been an often bitter struggle for power between Republicans and Democrats in Arlington. When Ford was hired, the power of the Democratic majority and the liberal Arlingtonians for a Better County, was wannng in the face of a national rebellion against property taxes.

Once a liberal stonghold in the tradionally conservative Virginia suburbs, a long line of Arlington Democrats prided themselves on improvements to schools and social services. But to many, the emergence of a conservative Republican majority in 1979 signaled a clear mandate for a tigher grip on spending.

Since then, the county board has engaged in vituperative battles with county and school employes, refusing to grant recommended pay raises. To the delight of many homeowners, it has also cut Arlington's property tax rate, making it one of the lowest in the Washington area.

"We constantly find [Ford] in an adversary role rather than that of a helpful lieutenant," Republican Grottos once said. She said Ford should "always defer to the will of the majority of the board on any given issue, ; or resign."

Yesterday, Detwiler confirmed that the majority had decided to look for another county manager but declined to cite specific reasons for Ford's dismissal.

Ford has been unavailable for comment since the announcement was made.