Rockville City Police Chief Charles R. Wall, who openly feuded with former Montgomery County Police Chief Robert J. diGrazia over the importance of the small, community-based police force, has resigned to become chief of police of Morgantown, W. Va.

During his five-year tenure, Wall tripled the budget and increased the force from eight policemen to 26 uniformed officers, including several who were paid with federal funds to operate a model burglary prevention program.

When diGrazia assumed office, he blamed the growing Rockville city police force for hampering county investigations, "We fought philosophically, professionally, and physically if I could have gotten my hands on him," Wall said. The friction from the top, Wall says, filtered down within the two departments.

Wall, who said he is leaving for professional advancement and not out of dissatisfaction, says the two departments have resumed a cooperative relationship since diGrazia's firing in December.

Wall who will assume the West Virginia job May 11, insists there continues to be a place for a small town police force. "we simply cost less than the county per officer, and we can provide closer, more personal service," including a lower overhead which allows 90 percent of the force to spend its time on the streets.

Wall says the number of calls to the city police have increased 300 percent in the last two years, to 40,000 calls in 1978. "And you can't reach us through 911. You've got to go out of your way to dial seven digits. Somebody must like us."