The Cambridge City Council last night may have killed a proposal referendum that would ban the manufacture of nuclear weapons in the city.

By a four to four vote the council failed to pass a motion to place the Nuclear Free Cambridge proposal on the November ballot.

Referedum proponents insisted after the meeting that approval was unnecessary and that as long as their proposal had the proper number of certified petition signatures it would go before the voters.

But the city manager for opponents of the referendum said that state law requires council backing for a binding initiative to be placed on the ballot and that the lack of a majority meant the effort had failed.

All sides agreed that the statute in question is hazy and conceded that the state election commission will likely be forced to interpret it. It is doubtful that either party would accept that ruling however and the matter could well end up in superior court lawyers for both sides predicted.

Last night's motion was the second attempt by opponents in a week to keep the question off the ballot. On Thursday lawyers for Cambridge's Charles Stark Draper Laboratories--a nuclear research firm which would be seriously affected by the measure--challenged the validity of petition signatures before the state ballot law commission. The commission which is separate from the state election panel continued hearings yesterday and is required to issue a ruling by Thursday.

Lawyers for Nuclear Free Cambridge and for Draper Labs have hinted that if that commission's ruling does not go their way they will also take that judgement to a higher court.

Even if the referendum overcomes both of these challenges, it will not be in the clear legally. Should it emerge from the courts in time to make the November ballot, and should it secure the necessary voter approval. Draper officials have promised to battle the law's constitutionality.

While a handful of local companies would be affected by the question. Draper has the largest stake in the current fight--85 percent of its work goes toward development of the MX missile, the Trident class submarine and other nuclear weapons, officials have said.

The Central Square lab employs about 1800 workers. Although the proposal--which would go into effect in October 1985--would relocate effected workers, organized labor has joined the opposition. Mayor Alfred E. Vellucci told his fellow councillors.

The city council vote came after more than an hour of confusing legal discussions, and a heated exchange between Councilor David Wylie, a strong supporter of the measure, and Draper Vice President John F. O'Connor. A large crowd of observes, which spilled over into halls and the upstairs galleries, stayed for the whole discussion, despite the sweltering heat mitigated only by one small clacking electric fan.

Wylie, who often raised his voice in an impassioned speech in favor of the measure said, "We are in more danger than we have ever been in the history of this city. We've never been more concerned that at the push of a button this whole city can be destroyed."

O'Corner responded that the Soviets would strike retaliatory missiles first and noted that Draper does not contain any such weapons Wylie O'Corner said was "misleading" the voters.

When the question finally came to a vote, the councilors split along customary partisan lines. The four members of the Independent slate--considered the city's conservative faction--voted no. They were Daniel Clinton. Thomas Danehy. Leonard Russell, and Walter J. Sullivan Three Cambridge Civic Association (CCA) members--Francis H. Duehay '55. Saundra Graham, and Wylie--joined the unaffiliated Vellucci in voting yes David Sullivan, the fourth (CCA) member, did not participate in the vote, saying that his position with the state election commission placed him in a conflict of interest.

After the meeting, lawyers for both sides expressed partisan sentiments as strong as those evident in the council vote.