The poundings he absorbed from Larry Holmes, Earnie Shavers and Scott LeDoux after he got a brief taste of the world heavyweight championship he so long pursued only set up Ken Norton for the inevitable.

Norton called an end to his boxing career yesterday, and the finishing blow was the death of Bob Biron, his gentlemanly manager and longtime confidant, Sunday night in Rancho Santa Fe, Calif. Biron, 67, never recovered from surgery for a brain tumor in December

"I can't go on without Bob," Norton said in Los Angeles after the news arrived from his hometown San Diego. "When we first started boxing together, Bob and I, we made a pact. If anything happened to me, he would quit and if anything happened to Bob, I would give it up."

Biron left the post of vice chancellor for finance, University of California at San Diego, and with four other men bought Norton's contract for $80,000 in 1971; he took over as manager.

Norton flashed to fame by breaking the jaw of Muhammad Ali in a 1973 nontitle bout, outpointing the past and future champion. But Norton lost their rematch for the title, and it was only later, by World Boxing Council fiat upheld by court of law, that Norton ever donned the championship belt. And in his first defense, Holmes took it.

Still, Norton has become wealthy -- Biron made sure of it with wise investments for him, associates say -- and if Norton's acting career (on which he intends to concentrate) fades, he'll get by.