Forget California on June 5. Never mind who will win New Jersey. The Democrats will nominate Walter F. Mondale for president, and Sen. Lloyd Bentsen (D-Tex.) will be his running mate.

At least that's the judgment of the 1984 Mock Democratic Convention, meeting in noisy session for the 18th time since 1908 at Washington and Lee University here in the Shenandoah Valley. The two-day political extravaganza, known for its raucous realism--right down to beefy security guards, demonstrations and vote trading--climaxed two years of planning and monitoring of the ongoing Democratic contest.

But it was mostly an academic political exercise for Washington and Lee, a proud all-male school with a predominately white and privileged student body. And despite strong Republican leanings, the mock conventions have accurately forecast the out-of-power party nominee 12 times, including Carter-Mondale in 1976.

They'll have to wait until July to learn if the Democratic National Convention in San Francisco will follow their lead this year, although the mock delegates were in constant contact with real Democratic Party officials throughout the state during the convention. Mondale won a close victory on the first ballot, but Bentsen won on the second ballot only after a spirited floor battle in which he edged out Rep. Geraldine Ferraro (D-N.Y.), who one delegate leader called "the fox from Flatbush" before casting his group's vote. In the real Democratic contest, Mondale holds a commanding lead in delegates. Both Bentsen and Ferraro have been prominently mentioned as potential running mates.

Colorado Sen. Gary Hart, who placed second to Mondale, faded as a choice for the second spot on the mock convention floor.

Virginia Gov. Charles S. Robb picked up about 30 votes in early balloting for vice president--most from Virginia--and there were scattered votes for such personalities as tennis star John McEnroe, former auto maker John Z. DeLorean and TV magnate Ted Turner.

The convention of 1,313 delegates--roughly one for every three at the real Democratic National Convention--had a little trouble sometimes submerging their Republican leanings.

They cheered heartily when the mayor of Lexington saluted them as "fellow Republicans who are weekend Democrats."

Sen. Ernest F. Hollings (D-S.C.), one of several national Democrats who addressed the delegates, joked, "This isn't a Democratic convention, this is a Republican ambush."

The convention lacked the drama of some past conventions--former vice president Alben Barkley dropped dead on stage here after a spirited speech in 1956--but officials did yank the float of the Massachusetts delegation at the opening day parade Friday. It featured a pool table with a female dummy on it, a reference to a sensational rape trial in New Bedford.

Few blacks attend the school and fewer still took part in the convention. One white Jackson delegate seemed to mirror the sometimes bizarre mix of loyalties, waving a Confederate flag on a lacrosse stick.

Sen. Joseph R. Biden (D-Del.) seemed to capture the fancy of the convention in a rousing speech Friday night in which he denounced the failings of both political parties.

"What kind of country is this to have moved from a standard of, 'Ask not what your country can do for you,' " Biden said, to what he said was the selfish question, "Are you better off now than you were four years ago?" He said the delegates should ask whether the country is better off with huge budget deficits and struggling foreign policies.

But one 18-year-old delegate, Thomas E. Myers of Roanoke, one of the few real Democrats at the convention, suggested the speech wouldn't have much lasting effect.

"A lot of people are straight party line--they're not opening their eyes. They're worried specifically about their family wealth . . . they're not worried about the little man."

The convention got a traditional telephone call from the winner's camp, with Mondale's chief delegate counter telling them, "Today America has everything to build on for the future except the leadership to take us there."