Virginia Gov. John N. Dalton, refusing to leave patronage plums for the state's victorious Democrats, yesterday named appointees to two state highway commission slots recently vacated amid conflict-of-interest charges.

The Republican governor said James C. Hughes, vice president of a McLean consulting firm and a GOP activist in Northern Virginia, and James C. Clore, a farmer and retired Culpeper funeral director, have been selected for the positions, effective immediately.

Dalton's action may mean that Democratic Gov.-elect Charles S. Robb may have to wait until mid-1982 when the two appointees' terms expire to name his first members to the influential highway panel.

Both seats fell vacant this fall after Dalton appointees William B. Wrench of Springfield and T. Ray Hassell III of Chesapeake resigned over conflict-of-interest allegations that quickly became an issue in the state's governor's race.

Dalton's decision to fill them drew criticism from some Northern Virginia Democrats, who argued Wrench's seat representing the populous Washington suburbs and the state's Culpeper highway district seat, should remain vacant until Robb takes office Jan. 16.

"How do you expect a Culpeper funeral director to be knowledgeable about Northern Virginia roads?" asked state Sen. Edward M. Holland, an Arlington Democrat. "That concerns me."

"It doesn't sit well at all with me," said state Sen. Clive DuVal, a Fairfax Democrat, "and I don't know whether we're going to confirm them."

Holland said it was too soon to predict whether the Democrat-dominated state legislature would balk at approving Dalton's choices. The General Assembly is scheduled to meet on Monday.

Dalton spokesman Charles Davis defended the governor's action, saying Dalton simply was fulfilling his obligations. Davis also noted that an urban at-large seat filled by a commissioner from Tidewater for seven years now goes to Hughes, an executive at BDM Corp. in Northern Virginia.

Fairfax County Board Chairman John F. Herrity said he was ecstatic about Hughes' appointment. Herrity, a Republican, has led a prolonged fight by the county against state highway officials over the proposed location of the Springfield Bypass, a major new north-south artery to cut across congested Fairfax. Herrity also was angered recently at suggestions that Dalton would pick a resident of Prince William County -- not Fairfax -- for the highway commission.

In naming Hughes, Herrity said, Dalton picked a former top Herrity campaign aide and member of Fairfax's Economic Development Authority. "I feel more optimistic about the bypass fight than I did a few days ago," Herrity said. "I think we're talking a new ball game in terms of alignment of the road ."

Herrity said he hoped Hughes would help persuade state highway staff members to meet soon with Fairfax planners to discuss differences over the proposed route -- a task Herrity said he had been trying to accomplish since August. Robb has said he supports the county's route.

Davis said he was unaware of the appointees' political leanings, but added, "I can guess." A spokesman for U.S. Rep. J. Kenneth Robinson, whose district includes Culpeper, described Clore as a close personal friend of the longtime Republican congressman. Hughes reportedly was recommended to Dalton by Republican Rep. Stanford Parris of Fairfax.

Four of the commission's 10 positions, including the two filled yesterday, will expire next June, leaving Robb free then to make his own selections. Although the job pays only $35 a day plus expenses up to $2,000 a year, the slots are sought after as powerful positions affecting the state's major road-building and maintenance programs.