With a ringing endorsement of the FBI's controversial Abscam undercover techniques, a federal judge in New York yesterday rejected pleas from four former congressmen to overturn their convictions because of government misconduct, and instead ordered them to appear for sentencing Aug. 13.

U.S. District Court Judge George C.Pratt's 136-page ruling in favor of the government was not unexpected, but Justice Department officials were pleased by the strong language he used in defending Abscam and excoriating the defendants' actions. Thomas P. Puccio, the chief prosecutor in the case, said he was delighted.

Pratt wrote, "Depsite their respected and trusted positions, defendants' crass conduct here reveals only greed, dishonesty and corruption. The government's need to unmask such conduct more than justified the investigative techniques employed in these cases. Without question, these convictions were reliable, and no constitutional right of any defendant has been infringed."

At one point in the opinion, the judge went so far as to call the seven defendants worse than drug pushers:

"The cynicism and the hypocrisy diplayed by corrupt officials, pretending to serve the public good, but in fact furthering their own private gain, probably pose a greater danger to this country than all of the drug traffickers combined. Corrupt leaders not only betray their constituents, but also contribute to a moral decay in American society that many view as the forerunner of economic, political and social disaster."

His ruling applies to the convictions of former representatives Frank Thompson (D-N.J.), John M. Murphy (D-N.Y.), Michael (Ozzie) Myers and Raymond F. Lederer, both Philadelphia Democrats, and three co-defendants, Angelo J. Errichetti, mayor of Camden, N.J., Louis C. Johanson, a former city council member in Philadelphia, and his law partner, Howard L. Criden.

Pratt also heard the case of Sen. Harrison A. Williams Jr. (D-N.J.), the last member of Congress convicted in Abscam. The judge didn't rule yesterday on the senator's due process motions, but he went out of his way to attack Williams' conduct. Williams is facing disciplinary hearings before the Seante Ethics Committee tha tcould lead to his expulsion. The hearings are to resume Tuesday.

All the defendants in Pratt's court were convicted of taking cash from undercover FBI agents who posed as representatives of a fictitious Arab sheik in fron of hidden videotape cameras.

All but Murphy face up to 15 years in prison on bribery convictions. Due process hearings of former representatives John Jenrette (D-S.C.) and Richard Kelly (R-Fla.), convicted of similar charges in Washington, are pending.

Criden's attorney, Richard BenVeniste of Washington, said yesterday that he wasn't surprised by Pratt's ruling. Noting that a federal judge in Philadelphia overturned the Abscam convictions of two Philadelphia city councilmen last fall because of government misconduct, he said he felt there is "a strong possibility that these important constitutional issues ultimately will go to the Supreme Court."

He added he was optimistic that the Abscam techniques eventually would be "repudiated as unconstitutional."

Appeals could take another year or two, attorneys on both sides agreed.

Pratt's blistering opinion demolished every defense attorney argument. He said, for instance, that claims that undercover informer Mel Weinberg's "coaching" session of Williams before a key meeting with the phoney Arab "sheik" used in the FBI scheme was neither grossly impropoer nor typical of the operation. He noted that the senator trestified that he paid no attention to Weinberg and that Williams "was not a weak, naive, inexperienced person."

The judge also criticized the testimony of federal prosecutors from New Jersey who, as defense witnesses, had attacked Weinberg and other elements of the investigation. The men were "jealous" of the importance of the case and "embarrassed" that someone outside their district had "uncovered a cesspool of corruption," Pratt said. He also faulted them for not pursuing Abscam aggressively in New Jersey.

Pratt also rejected defense arguements that the congressmen were unfairly targeted by unsuspecting middlemen. He said they were not selected by government agents "for some sort of 'honesty test.' Instread, each was a willing volunteer seeking illegal and corrupt payments."