The House yesterday approved procedures for debate on the extension of the Voting Rights Act, opening up prospects for a free-for-all over what is generally agreed to be the most effective civil rights bill ever passed by Congress.

Strains were clearly evident in the bipartisan coalition in the House Judiciary Committee that has supported civil rights legislation for the last 25 years, as the House approved a rule allowing unlimited amendments. Committee Republicans warned that they intend to offer a host of amendments to weaken the bill, which the panel approved before the August recess with only one dissenting vote.

The strongest, and most pointed challenges apparently will come in two areas: bilingual language requirements, and in setting "bailout" procedures for local and state governments, mostly southern, that are covered by the bill.

Rep. Robert McClory of Illinois, the ranking Republican on the committee, set the tone for the debate, saying vast changes have taken place in voting patterns since 1965, when Congress first passed the landmark legislation. Almost 60 percent of the blacks in Louisiana and Mississippi now vote regularly, compared with only 40 percent of blacks in such northern states as New York and New Jersey, he said.

"It's high time changes in the act be made to reward areas which have shown progress," added McClory.

The bill attempts to do this through bailout procedures. They would allow states and local jurisdictions that have complied with the law for 10 years to escape requirements that they get prior clearance from the Justice Department for any change in their election laws.

Civil rights groups maintain that almost one-fourth of the jurisdictions, most in the South, now covered by the act, would qualify for bailouts by 1984. To do so, a jurisdiction must prove it has used no literacy test or similar device, has fully complied with the pre-clearance requirement, has not been found guilty by a court of abridging the right to vote, has not needed federal examiners sent in to enforce voting rights, and has engaged in constructive efforts to eliminate intimidation.

But Rep. M. Caldwell Butler (R-Va.) argued that several of the bailout procedures discriminate against the South. He voiced particular distaste for requirements that would place approval for all bailouts in federal district court in Washington, and would keep any state from qualifying until every jurisdiction within its boundaries did so.

The Leadership Council on Civil Rights, a coalition lobbying for the bill, opposes any changes in bailout procedures. "Liberalizing the bailout is a code word for not extending the act," said Lani Guinier, an attorney for the NAACP Legal Defense Fund.

McClory and Rep. Daniel Lungren (R-Calif.) also said they will introduce amendments to eliminate provisions that require areas with non-English speaking populations of 5 percent or more to provide registration and voting information in minority language. These provisions don't expire until 1985, but Hispanic groups fear a backlash against them and have lobbied to include them in the voting bill. Full debate on the bill is set for Wednesday.