When it was over and the Democrats had rewritten their nominating rules for the fourth time in 12 years, the chairman of the latest Democratic "reform" commission, North Carolina Gov. James B. Hunt Jr., said what his predecessors have always said under similar circumstances.

He said the new rules "will help us win and help us govern."

The history of the Democrats' past decade of experiments in presidential-selection "reforms" is such a saga of unintended consequences that prudence dictates caution on any guess about the impact the new rules will have on the party's 1984 contenders and the chances of one of them becoming president.

Nonetheless, there was fairly widespread belief among the rule-writers and the candidates' agents that Hunt may be right. One reason was that the rewrite process that ended Friday was less bloody than in previous rounds. There were none of the tears and less of the shouting that marked past commissions and no caucus threatened a walkout unless its non-negotiable demands were met.

Nit-picking is the chronic illness of Democratic Party rules commissions, but this one, miraculously, barreled through its agenda and finished a day ahead of schedule.

One reason was expressed--in terms too blunt for a family newspaper--by John Perkins, the new director of the AFL-CIO Committee on Political Education. "When Ronald Reagan is kicking the stuffing out of you," Perkins said, "you get a lot more conciliatory. You realize your real enemy is not someone in this room."

A second reason was that Hunt negotiated a lot of agreements in advance with Perkins, key state party chairmen, congressional leaders and representatives of potential 1984 rivals Walter F. Mondale and Edward M. Kennedy. When Kennedy's man, Jack English, found all the others lined up against him in their desire to bring in large numbers of elected and party officials as uncommitted delegates, he threatened just hard enough to bring the percentage down from 30 to 14 percent of the convention strength--and then gave in.

On all but the most marginal issues, the Kennedy, Mondale, labor, state party and congressional representatives on the commission were aligned on the same side--producing lopsided votes.

A third reason for the absence of bitter controversy was that Hunt & Co. did not even attempt the massive restructuring of the nominating system that many academic and journalistic critics had urged on them. They did nothing likely to reduce the number of primaries, the length or cost of the campaign or the influence of the news media.

While moving the Iowa caucuses back five weeks to late February and the New Hampshire primary back a week to early March, they guaranteed those small states their early-bird status--and the massive, disproportionate publicity bonanza that goes to the winners of their delegate contests.

As a result, most of the political scientists who served on the commission's technical advisory committee said that the system is probably as "front-loaded" as it ever was. And that means, in their judgment, it remains open to exploitation by the self-starting, early-starting, full-time "outsider" candidates following the paths of Jimmy Carter, George Bush and Ronald Reagan from the Grange halls and Lions clubs of Iowa through the shoe factories and fire stations of New Hampshire.

Nonetheless, the Hunt commission did clear up some bits of foolishness in the old system and it changed the rules and players in ways that may become significant in 1984.

It ended what was clearly the dumbest rule in the 1980 convention: the absolute requirement that a delegate vote for the candidate to whom he or she was orginally pledged even if, as was said at the 1980 rules committee, that candidate "has been convicted of a triple ax-murder" in the interim. Now, the delegates are directed to keep faith with the "sentiments of those who elected them" as best they can determine them at convention time.

It invited about 550 unpledged elected and party officials to occupy about one-seventh of the convention seats. These officials may or may not be honest brokers, since one of the new rules--dubbed the "instant virginity" rule--allows people who have previously pledged to a candidate to be selected as uncommitted delegates.

But the choice of these delegates by the Senate and House caucuses and the Democratic state committees opens up a new arena in which the candidates will have to play. And in a close contest, if most of the 550 really are uncommitted, they could in fact become what their critics on the Hunt commission fear: "super-delegates" or king-makers.

The fact that Kennedy's agent, Jack English, bargained hard to reduce the number of uncommitted delegates suggests that Kennedy does not assume, at this point, that he ranks ahead of Mondale in the sentiments of those elected officials and party big-shots.

On the other hand, Kennedy was judged by some observers to be a potential beneficiary of one of the other major changes made by the Hunt commission, the restoration of "loophole primaries." The "loophole primary" is one in which voters cast ballots directly for individual delegate candidates; it allows the plurality winner in a congressional district to win all its delegates.

Until it was banned in 1980, as a violation of the proportional representation rule, the "loophole primary" was a used in such big urbanized states as New York, Pennsylvania, Ohio, Illinois, Texas, New Jersey and Maryland. Those who see Kennedy primarily as an urban candidate think he will gain from their going back to the "loophole primary." But others note that he lost half those states in 1980 when Mondale was doing most of the campaigning for the Carter-Mondale ticket.

Any such calculations are likely to be revised when the Democratic National Committee reviews--and perhaps alters--the Hunt recommendations, and the states then choose their own methods for picking their 1984 delegates.

There is speculation, for example, that the DNC may increase the number of unpledged delegates in order to balance the predominantly white male office holders with more women and minorities. And there is talk of major changes in the 1984 primary calendar, with particular attention to the possibility that California may move its primary up from early June to early April in order to gain greater influence than it had in 1980, when Kennedy was its favorite.

As of now, it is possible to argue that the new rules favor Mondale, or Kennedy, or that ambitious unknown who will virtually live in Iowa and New Hampshire through all of 1983. But the history of Democratic rules is--unintended consequences.