"Blow Torch" Bob Komer, third-ranking executive in Jimmy Carter's Pentagon for the past four years and before that a cage-rattler in high government posts from Vietnam to Turkey, left office yesterday firing a final volley at hidebound military thinking.

The Army, Navy, Air Force and Marine Corps are "all trying to have their cake and eat it too" these days by asking for extra billions to buy doubtful weapons before putting forces they already have in fighting shape, Komer complained in a farewell interview.

He dismissed as propaganda last week's claim by Navy leaders that they had lost their edge to the Soviet navy. They failed to count what allied navies would contribute in a war and to mention how vulnerable the Soviet fleet really is, Komer said.

Besides that, he continued, if the Navy wants more ships for the Indian Ocean in a hurry, its leaders should face up to the fact that Air Force planes could cover Soviet ships in the Mediterranean, freeing the U.S. Sixth Fleet for duty elsewhere.

"The one mission in the Mediterranean that land-based air might not be politically available for would be an Arab-Israeli contingency," Komer said, but that threat has been reduced by the signing of the Egypt-Israeli peace treaty. The Mediterranean, he continued, has become "a place where I think we could do without a two-carrier task force and stick it in the Indian Ocean."

A big part of Komer's job as undersecretary of defense for policy for the past four years has been to recommend ways to protect U.S. interests in the Middle East and Persian Gulf. He said some of the military thinking he ran into "drove me up the wall. Like this business that the Navy must have 600 ships. The problem is capability, not numbers." If the sole criterion were numbers, he said, "We could have a 1,000-ship Navy if we built sub-chasers."

The Marines, Air Force and Army have their fixations, too, Komer said, which get in the way of planning realistically for the changed world of the 1980s and 1990s, when much of the Third World is expected to be in turmoil and amidst a scramble for its resources, particularly oil.

"The Marines are still too . . . wedded to what I regard as an out-of-date doctrine of amphibious assault being the key element of the Marine mystique," Komer said. Marines will find themselves land-locked on Okinawa if they wait until there are enough assault ships to sail them to the Persian Gulf, where landings will most likely be unopposed.

"As the chief civilian thinker in the Defense Department, I look around at the range of contingencies, and I don't see that many requirements for a major amphibious assault, period," Komer said.

The Air Force does need billions of dollars to modernize, he said, but may squander it on a vulnerable bomber like an updated B1 in a $50 billion splurge. "The institutional mystique of the Air Force is that if we don't have a manned bomber, the Strategic Air Command is going to be just a bunch of missile engineers."

Planes like the CX for transporting troops and their gear long distances is the real need of the day for the Air Force, he said, not a manned bomber like the B1. The task of getting a nuclear bomb to the Soviet Union can be accomplished more cheaply and reliably with the cruise missile, launched far from Soviet air defenses, Komer said.

"To push for a B1 that will be obsolescent before the first production model takes off from the runway seems to me sort of dumb," he said, adding that a truly advanced bomber like the hard-to-detect Stealth would make more sense.

Komer said the Army, in which he served as first lieutenant staff officer druing World War II, until recently has been hung up on the assumption that it would need heavy armored forces in Europe, as distinguished from lighter but faster infantry outfits. But the Army is now changing and going for a mix, he said, giving one bit of applause.

Komer recommended stationing an Army helicopter brigade in Europe to back up the North Atlantic Treaty Organization front line and to respond to Persian Gulf emergencies. Although Army leaders agree with him, "One of the things I learned in the Pentagon is that just because the Army chief of staff and the NATO commander want something, they still have got to get it through the . . . bureaucracy," he said.

Komer, 58, who expects to wake up classes at George Mason and George Washington universities, where he will lecture on foreign affairs in his new life as private citizen, directed one of his hottest blasts at Japan for not doing more militarily.

Komer, who likes the "Sly Old Fox" nickname given to him by the North Vietnamese during the Vietnam war, when he was head of pacification in the south, took the pipe out of his mouth and said, with uncharacteristic softness:

"The American taxpayer has been paying unconscionably for the defense of Japan. We provide the nuclear umbrella, we provide the high seas capability, we're defending their oil. They need it a hell of a lot more than we do. Yet they are spending only nine-tenths of 1 percent of their gross national product on defense. I'm embarrassed for the Japanese. I would think the Japanese honor would not allow them to be so supine."