Egypt has entered into a delicate unwritten agreement with the major American corporations to help them get off the Arab boycott list is they will invest in industrial operations here, according to authoritative Egyptian and American sources.

The five are prepared to invest in Egyptian projects that may not be profitable if Cairo succeeds in opening the door to the lucrative markets in the rest of the Arab world, the sources said.

"They know they aren't going to make much money here," said a high-ranking Egyptian Foreign Ministry official involved in the negotiations. "They want to sell in Saudi Arabia. And we are the only country with the prestige and the political credentials to take their case to the boycott commission."

Egypt to this point has had only minimal success in attracting the Western and especially American capital investment that it desperately wants.

The attempt to remove these five corporations from the boycott list represents an inducement to attract them into projects here that might not be economically attractive on their own, these sources say.

The five firms are Coca-Cola Co., Ford Motor Co., Nerox Corp., Motorola and Colgate Palmolive. At least four of them have received preliminary approval from Egypt's General Authority for Foreign Investments, but implementation of their projects is understood to be awaiting the outcome of Egypt's efforts to have them removed from the blacklist.

"We gave our approval on the basis of economic projections for the benefit of the country," said Metwalli Atallah, assistant to the director of the investment authority. "Our approval is given on the condition that there is no problem on the political side. We sent a recommendation that these are good projects but it is not our business to make the political decisions."

Foreign Ministry officials have confirmed that the basic political decision to appeal to the Arab Boycott Commission for the removal of the five from the blacklist has been made, after a long debate within the government.

Anxious as it is for foreign investment to shore up its sagging economy, Egypt may be prepared to allow blacklisted corporations to come here even if the Arab Boycott Commission refuses to clear them for operations in the rest of the Arab world. It would not be the first time an Arab country had put its own national interests ahead of the boycott requirements.

It is not clear, however, whether the American corporations are prepared to go ahead with their projects here if the prize they really seek, removal from the boycott list, is withheld.

The two projects that are furthest advanced in planning and commitment are those of Ford and Coca-Cola, both blacklisted for many years because of their operations in Israel.

Ford proposes to reopen a plant in Alexandria that was closed after its blacklisting in 1966, and to built a new plant for manufacturing truck engines.

Coca-Cola signed an agreement last month to participate with Egyptian investors in the development of citrus groves on 15,000 desert acres near the Suez Canal.

The signing ceremony took place at the Ministry of Agriculture, a rare public display by an Arab government of cooperation with a blacklisted firm. Coca-Cola vice president Sam Ayoub told reporters at the time he was "very hopeful" that Coca-Cola would be removed from the blacklist.

For Ford and Coca-Cola, the arrangement with Egypt offers an opportunity to crack the markets of Kuwait, Saudi Arabia, Libya and other oil-rich states, where vast quantities of Pepsi-Cola are consumed annually by prosperous Arabs driving Chrysler and General Motors cars. Informed sources here say that may still be a long way off, despite the bargaining with the Egyptians.

The next meeting of the Boycott commission is scheduled for November. Egypt may not be ready, analysts here say, to put its political prestige on the line for these American firms and defy criticism from Arab hardliners at a time when there is still so much uncertainty over Middle East peace negotiations.

If no action is taken in November, however, a new problem arises. After the end of this year, new American anti-boycott legislation will bar the U.S. firms from cooperating with or making information available to the Egyptian officials who are preparing the case for removing them from the blacklist.

The decisions of the boycott commission, taken in closed session, are unpredictable and often erratic. Some firms known to do business in Israel that clearly helps the Israeli economy have never been blacklisted, although it is the ostensible purpose of the boycott to discourage such dealings.

But observers here doubt that the commission would be willing to remove such well known symbols of American industry as Ford and Coke simply to suit the economic convenience of Egypt.