John Davidson recorded the New York Rangers'first Stanley Cup shutout in six years tonight as he blocked 28 shots in a 6-0 rout of the Philadelphia Fylyers.

The margin equaled the worst playoff defeat in the Flyers' 12-year hestory, a 7-1 massacre in Philadelphia on Wednesday. In three games, the Rangers have outscored the Flyers, 18-2, while building a 3-1 lead in this best-of-seven quarterfinal.

If New York wins one more, it will mean a semifinal series against the Islanders, but Davidson quickly ended conjecture in that direction.

"We've got to win this one first," Davidson said. "They're going to be tough Tuesday (in Philadelphia). They've got a lot of pride."

Don Murdoch and Eddie Johnstone scored two goals apiece tonight and each had one in the first seven minutes while both teams were a man short. When Phil Esposito and Bob Sheehan connected in the first six minutes of the second period, there was little left for the Rangers to do but avoid injuries from the frustrated Flyers' foul play.

They did not succeed completely, since defenseman Dave Maloney suffered a severe charley horse when Paul Holmgren took a run at him in the third period. Holmgren was assessed four of the Flyers' 11 penalties and referee Andy Van Gellemond seemed to deliberately overlook some more violations, perhaps to prevent the Flyers from using the penalty totals for an alibi.

Murdoch, who missed the first 40 games of the season following his conviction on a drug charge, has scored four times in the last three games. Tonight he fired eight shots, a Ranger playoff record, at Flyer goalie Robbie Moore and he attributed his recent success to concentration.

"I hadn't been concentrating the way I usually do on my shots," Murdoch said. "I've been more or less trying to get them off, whether I had to rush or not, instead of taking an extra second for a better look when I had the chance."

Johnstone, only 5-foot-9 and 175 pounds, is a bench-warning winger who has been utilized as a playing center in the absence of Uif Nilsson.

"I'm pleased Fred (Shero) had the confidence to put me out there." Johnstone said. "It's kind of new and I've been turning the wrong way and the faceoffs have been tough. But I'm glad to be out there at any position."

"His size is against him," Shero said, "I've always leaned to bigger guys, but sometimes I think I'm wrong and a lot of people in hockey are wrong. I had one nibble for him, but I was afraidto let him go. He's honest and I know he can do a job. He takes the body and he'll fight anybody."

Davidson had some assistance from the cage behind him as he reduced his goals-against average for six playoff games to 1.14.

With the Flyers trailing 2-0, Behn Wilson's shot from the point was deflected on the way toward the net. It struck the crossbar, caromed off the right post and dropped behind Davidson in the crease, where Philadelphia's Bobby Clarke overskated it and, turning back, could not get his stick on the puck.

With the score 4-0, Bill Barber defected a Bob Dailey shot that slid past Davidson off the post.

With the score 6-0, the Flyers turned on the red light-in vain. After a Dailey shot was deflected high in front , Al Hill knocked it into the net with his glove. It did not count. CAPTION: Picture, A Stanley Cup Save; Boston goalie Gerry Cheevers sweeps puck off stick of Pittsburgh's Ross Lonsberry, Boston, Montreal and New York Islanders won quarterfinal series, and New York Rangers beat Philadelphia, 6-0. UPI