Imagine a billion dollars.

Four thousand cubic feet of money, according to U.S. Treasury officials. Enough single dollar bills to circle the earth nine times at the equator.

With that kind of money, the University could buy every undergraduate a top-of-the-line, fully loaded Mercedes-Benz 600 SEL.

And President Neil L. Rudenstine hopes to raise nearly twice that amount during the next six or seven years--the largest fund drive in the history of higher education.

Harvard administrators are reluctant to speculate on precise goals for the long-expected capital campaign. Their most recent estimates--significantly less than the $2.5 billion ballpark figure under discussion just a few months ago--could be indicative of growing concerns about the obstacles such an enormous campaign will face.

But Harvard insiders say they are not making predictions simply because Rudenstine has not yet set an exact target. They point out that the president continues to meet, as he has over the past year, with top deans and vice presidents to assess the University's long-term needs and set an official goal.

Still, work on the campaign has already begun and an official announcement is expected near the start of the 1993 academic year.

Many say the timing is less than ideal.

The kickoff will likely occur in the midst of a continuing national eco- Snomic downturn and in the wake of severalwidely-publicized financial scandals at thenation's elite universities.

It will come on the heels of billion dollarcampaigns at other universities--including MIT,Stanford, Yale and the University ofPennsylvania--that could draw major donors awayfrom Harvard.

In addition, some educators are attacking thevery concept of universities holding mammothcapital campaigns.

Peter M. Buchanan, president of the Council forAdvancement and Support of Education (CASE), saidat the group's annual conference in July thatlarge fund drives shift a university's focus to"money rather than education."

Buchanan, the former vice president fordevelopment at Columbia, told the group thatcapital campaigns are "the dumbest thing I think Ihave ever seen."

But fundraisers at several universities disputeBuchanan's argument, and Harvard's fundraisingchiefs remain optimistic about their prospectsdespite the awkward timing.

"I don't think there is ever a good time, butit would have been nicer to raise it in theeighties, probably," says Peter L. Malkin '55, amember of the Board of Overseers and a majorcontributor to the University.

"It's going to be difficult to raise it nowbecause of the economy. But I think people will bevery convinced by the case that will be presentedabout what the University really [needs]. I thinkthe case will be very persuasive."