Arlington County Manager W. Vernon Ford proposed yesterday the county grant its workers a 9.5 percent pay increase next year and urged that spending for Metro and schools be held below the levels others have recommended.

His proposed $173.5 million budget is based on the County Board's previously proposed cut of 8 cents per $100 of assessed value in the county's real estate tax. The cut will place the tax at $1.21 per $100 but is not enough to offset an average rise of 17 percent in home values during the past year.

County officials have said that they expect most homeowners in the county will see an increase of 9.7 percent in their real estate taxes under the Ford budget.

Ford's overall budget calls for a modest increase of 3.6 percent over this year's and contains funds for no new major programs.

Ford's budget, which must be adopted by the County Board before it becomes effective, places him and school Superintendent Larry Cuban $1.1 million apart on how much it will cost to run Arlington's public schools next year. It also places him $1.8 million under what the Metro transit board says should be Arlington's share of running the regional transit system. b

The spending gap will undoubtedly feed the smoldering feuding between Superintendent Cuban and his Republican-backed County Board Chairman Walter Frankland.

The County Board had told the school board earlier this year that it should ask for no more than a 5 percent increase over the $38.4 million that the county currently provides for school operations.

On Thursday night, Cuban asked that the county's contribution to his proposed $53 million school budget be set at $41.1 million, including a 10.5 percent pay raise for teachers and other employes, thus setting the stage for the perennial school budget struggle.

"This school budget is our biggest spending item," Frankland said during the lunch break yesterday. "Obviously, I am disappointed . . . because the superintendent's budget didn't come within guidelines."

The county budget also reveals sharp differences with the Metro board over what Arlington should contribute to the public transportation system. The proposed Arlington budget calls for a $9 million contribution to Metro -- $1.8 million below the $10.8 million that the Metro board has said is the county's fair share.

"I have no sense that our board will go to $10.8 million," said Anton S. Gardner, the county's chief of fiscal affairs. "I think our board will be firm to the end on this one."

Gardner said that the size of the county's Metro contribution has become a matter of principle. Arlington had told the Metro staff in the throes of last year's budget cycle that the county's anticipated contribution to Metro looked too low. It was not until late last month that the Metro staff conceded that it had made a mistake and asked Arlington to say more.

"The error then becomes compounded," Gardner said, because this year's subsidy level becomes the base for next year's, so that by 1986, Arlington would be paying 20 percent of locally collected revenues for its share of the subway-bus system.

A county fiscal staff versus Metro staff session on the issue is scheduled for Feb. 22. The Metro staff is likely to suggest that the county accept reductions in bus service if it wants to keep its budget figure. The county staff is likely to counter with recommendations for Metro system economies.

It appears, too, that the school and county pay raise requests may stir some controversy.Chairman Frankland predicted yesterday that an effort will be made to make the percentage of pay raises for school and county employes uniform.

Board members have indicated they may consider two highly popular measures -- cutting the personal property tax or reducing the vehicle license tax -- before the budget process is completed.

The tax rate must be set by March 15 and the board must adopt the budget by April 28.