Washington Capitals Coach Bryan Murray will shift center Bob Carpenter to left wing on a line with Bengt Gustafsson and Dave Christian, and he will elevate center Doug Jarvis from occasional duty to top-of-the-line status between Mike Gartner and Gaetan Duchesne when the St. Louis Blues visit Capital Centre tonight at 7:35.

There also will be a new man on the ice for the Capitals when right wing Ed Kastelic makes his National Hockey League debut. With Kastelic playing, several Washington wingers will be awaiting nervously the scratch list.

General Manager David Poile is due back today from a trip and Murray indicated that one or two players could be assigned to Binghamton of the American Hockey League.

Carpenter has been struggling, both physically and in the scoring column, so Murray felt it might help him to skate the wing a while instead of carrying a more onerous load at center. Almost the first move Murray made when he replaced Gary Green in November 1981 was to shift Carpenter, then a rookie, from center to left wing.

"Gus and Dave are going very well and it should be good for Bobby to play with them," Murray said. "But Bobby will also play some center ice. He'll start at left wing but maybe by the third shift he'll be at center ice with different people."

Carpenter suffered a pinched nerve in his neck Saturday and had to leave the 6-2 win over New Jersey after one period. He looked good in yesterday's practice and said he noticed only a slight problem.

"It pinches a little bit if I turn real quick, but it's a lot better," Carpenter said. "I was in traction the last couple of days and it helped a lot.

"I don't mind playing left wing again. It's an easy job, just forecheck and cover the point. And it'll be good playing with those two guys. I hope we can get something going -- me."

Jarvis has struggled a bit, too, and his ice time had been cut considerably. But after Carpenter was forced out Saturday, Jarvis responded well to an increased role.

"This is an upgrade for Doug," Murray said. "He's played much better lately and he's winning faceoffs consistently. He's the type of guy we count on in critical situations and this will give him more chance to get involved . . . "

Kastelic, 21, suffered a fractured cheekbone in an exhibition-game fight with Boston's Lyndon Byers Sept. 29. He skated with the Capitals until he was pronounced fit to play, then was assigned to Binghamton Oct. 20. In 18 games with the Whalers, he totaled six goals, seven assists and 74 penalty minutes.

Kastelic, 6 feet 2 and 200 pounds, has earned a reputation as a tough guy with limited skills, but reports out of Binghamton indicated that he was improving in all areas. When Kastelic turned in a five-point game against Rochester Saturday (two goals and three assists), he was called up in such a hurry he barely had time to pack.

"He's played extremely well in Binghamton and he's started to do some things," Murray said. "He's a big guy and a strong guy and if he can come up here and play tough, we can really use him. He has a chance to do some things for us offensively and he's improved his skating, which was the main drawback."

Kastelic is well aware that tonight's game could mean the difference between a big-league job and a return to the buses.

"This is a big game for me," Kastelic said. "I'm trying not to be too nervous, but of course I am nervous. Everything up here is at so high a tempo. I hope I can adjust quick. I was always hoping I'd be called up, but I wasn't expecting it. I was surprised it happened so suddenly. I just had an hour to pack and go."

No doubt feeling a bit nervous are the three players who skated as a fifth line in yesterday's practice -- David Jensen, Gary Sampson and Lou Franceschetti.

Jensen scored a sensational goal in his Washington debut Nov. 15, but he has dressed for only four of seven games since, receiving limited playing time.

Sampson netted the game-winner against Quebec Nov. 23, his only goal of the season, but has not played since. He has sat out seven of the Capitals' 24 games.

Although Murray likes Franceschetti's heavy hits, the zero in the goal column and minus-seven rating make Franceschetti vulnerable.