Ray Knight ignited a three-run rally in the seventh inning with a home run, climaxing another New York comeback and sending the Mets to their second World Series championship with a 8-5 victory last night over the Boston Red Sox.

The Mets scored three runs in the sixth inning, two on a single by Keith Hernandez, to chase Bruce Hurst, winner of two Series games, and tie the score 3-3. Then Knight led off the seventh with a homer to left-center that started the Mets to their first World Series title since 1969.

Hernandez capped the inning with a sacrafice fly for a 6-3 lead.

The Mets still had one last obstacle to overcome as the Red Sox rallied for two runs in the eighth and had the tying run on second base with no one out.

But Jesse Orosco came out of the bullpen and got Rich Gedman on a line drive to second, struck out Dave Henderson and got pinch-hitter Don Baylor to ground out to short.

Darryl Strawberry led off the eighth with a homer off Boston reliever Al Nipper. Orosco, batting for only the fourth time this season, singled in Knight with the eighth New York run.

Winners of major league-leading 108 games during the season, the big question about the Mets was how they would hold up under pressure. They had never been tested.

But they won their third National League pennant in a tense six-game playoff with Houston, culminating in the longest post-season game in history, a 6-5, 16-inning victory in the Astrodome.

After losing the first two games of the World Series at home, they became only the second team in World Series history to come back from 0-2 to win. The only other team to do it was last year's Kansas City Royals.

The Red Sox came back with Hurst on three days'rest, taking advantage of a rainout of Game 7 onSunday night. It was a gamble because Red SoxManager John McNamara had said Hurst didn't pitchwell on three days' rest. In his only otherappearance this season on three days' rest, heworked six innings and gave up three runs on sevenhits in Game 5 of the American League playoffs.

The Red Sox won that game 7-6 in 11 innings tobegin a comeback from a three-games-to-one deficitagainst California. This time, the Red Soxcouldn't quite make it all the way back.

And thus continued the sad saga of the Red Sox,losers of four straight seven-game WorldSeries--1946, 1967, 1975 and 1986. In fact, theRed Sox have not won a Series since 1918, whenBabe Ruth was still with the club.

In Game 6, they were one out away from winningit all, leading 5-3 with two outs in the 10thinning. But the Mets came back to score three runson three straight hits, a wild pitch and an errorby first baseman Bill Buckner.

Knight's homer came off Calvin Schiraldi, theloser in Game 6 who had come in to start theseventh for Hurst.

After Knight's homer, the 11th of the WorldSeries but the first by a home-team player, LennyDykstra came in to hit for Kevin Mitchell andsingled to right. Dykstra went to second on a wildpitch on a pitchout, and Rafael Santana singleddown the first-base line for another run.