House leaders yesterday sought to show that they are serious about adopting a new code of ethics by promising that tougher rules covering matters ranging from financial disclosure to outside income restrictions will be before the House by early March.

Rep. David R. Obey (D-Wis.), head of a House commission that will propose the rules changes, promised that the code would be before Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) by Feb. 8.

Testifying before the commission, which began hearings on the new code yesterday, O'Neill endorsed the timetable, and said:

"I intend, by the end of two year as Speaker of the House, that this House will have the strongest code of ethics of any constitutional legislative body in America."

The commission recommendations will go to the House Rules Committee and then to the floor. O'Neill said that on the day they are adopted as House rules he would appoint an ad hoc committee headed by Rep. Richardson Preyer (D-N.C) to write them into law and produce guidelines for the code.

Preyer said his job would be to decide on enforcement and to coordinate with the Senate, since when they are adopted as law they will affect the Senate as well. Adopting them as law also allows civil and criminal penalties to be set for violating the code. There are no evil or criminal penalties for violating House rules.

The Obey commission will make recommendations concerning financial disclosure, restrictions on outside income and gifts to members of Congress, unofficial office accounts funded by private contributions and use of the franking privilege.

The Commission on Executive, Legislative and Judicial Salaries has recently recommended that congressional pay be raised from $44,600 a year to $57,500, but said that increase should be tied to adopting a tougher code of conduct, particularly putting restrictions on outside earned income and honoraria for speaking engagements.

Testifying before the Obey commission yesterday, pay commission Chairman Peter G. Peterson said the pay increase would cost the public about $1.5 million, but added, "Money in politics is so corrosive that there would be a likely saving to the taxpayer by taking this step to minimize the influence of special interest far beyond the $1.5 million if would cost."

However, despite Peterson's enthusiasm for the proposal, the afternoon session of the Obey commission brought the first indication that getting the new code through the House might not be so easy.

Five House members, considered to be leading and influential reformers, were asked by Obey commission member Rep. Lee H. Hamilton (D-Ind.) to comment on some suggested concrete proposals.

Among the suggested proposals listed by Hamilton:

Full disclosure of all assets, liabilities, disbursements and other relevant holdings.

A limit on outside and earned income that would prevent members of the Congress from earnings more than 10 or 15 per cent of their salary from outside sources.

Limit to about $600 the amount that could be received in honoraria for any single speech and an overall limit on the amount of honoraria a member could receive.

Abolish outside office accounts, now funded by contributions, often from special interest groups.

No acceptance of gifts over $300 by the member.

No lame duck travel.

Ban the use of outside funds to produce any mail that is to be franked.

But Rep. John B. Anderson (R-Ill.), one of the longtime devotees of reform, bristled at the suggestion of a 10 per cent limit on outside income and the limit on honoraria. And longtime reformer Rep. Morris K. Udall (D-Ariz.) opposed limits on outside income, limiting honoraria, abolishing office accounts and abolishing lame duck travel.

On limiting outside income, Anderson said, "If you are serious about limiting outside income to between 10 and 15 per cent of a member's salary, I'll soon depart this place. I don't want to try to educate five college-age children with that."

Udall said, "I'm against a limit on outside income.You're saying there's a difference between earned and unearned income. You're saying if I have all kinds of inherited wealth in stocks and bonds it's okay. But if I got out on weekends and hustle and get some money from speaking engagements it's not okay."

Udall said his philosophy was to have full disclosure of everything, from office accounts to honoraria. "Then if my opponent can use what I made in honoraria or how I used my office account against me, and the people buy it, I will be defeated."

Rep. Robert W. Kastenmeier (D-Wis.) endorsed a limit on outside earned income, but thought 10 per cent might be too low. He suggested allowing $6,000 in honoraria.

He found some agreement among the commission members. The Obey commission is made up of eight House members, five Democrats and three Republicans, and seven "outsiders" from business, labor, academic and interest groups.