ITHACA, N.Y. Feb. 29--The heavily favored Crimson trackmen survived a succession of disappointing performances here tonight to edge Navy 43 1/2 in 42 and give Harvard its second Heptagonals championship in three years.

A capacity crowd of 4500 sat gasping at the finish as Midshipman pole vaulter Mike Brown, missed on three attempts at 15 ft., 8 in. Had he cleared the height, his team would have won the meet.

A series of misfortunes in the earlier action set up the dassling finish: Favored Art Croasdale took a disappointing fourth in the 35-lb. weight throw. Defending champion and Heptagonals record holder Aggrey Awori failed to qualify for the final heat of the 60-yard high hurdles. Favorite Walt Hewlett finished next-to-last in the two-mile run, almost a full-lap behind the winner. The mile relay team failed to score.

Even these disasters weren't enough to put Navy within reach of the title until Army's disqualification in the mile relay gave the Middies a surprise two points in the event. The ruling placed Annapolis' hopes squarely around Midshipman Brown's neck, just as he was chugging down the runway for his second assault of the 15 ft., 8 in. high crossbar.

The stocky junior missed on that attempt, and clutched on his final try. The failure gave him second place to Army's Dick Plymale and put half-smiles on the faces of Crimson coach Bill McCurdy and the Harvard runners, who embraced each other with half-hugs and jumped up and down in slow motion.

This final absence of a fully delectable enthusiasm was forshadowed from the first event. There a foul-prone Art Croasdale threw the weight 57 ft. 2 3/2 in., good for fourth place behind Navy's Bill Gleeson. Croasdale also took a so-so fourth in the shot put

A third place

Then Awori's failure to place in the hurdles final forced the Crimson to settle for a third position and three points from Tony Lynch. Another scant point came in the mile, as Bill Crain notched fifth place, far behind the winner, Bill Straub of Army.

Sweat became noticeable on the Harvard bench during the two-mile, as Walt Hewlett started slow and finished slower. The predicted six points for the Crimson vanished into none when Yale's Jeff Sidney, whom Hewiett defeated last week, led a pack of alien runners across the tape ahead of the Crimson sophomore.

Tonight's redeeming hero for the Crimson was captain Ed Meehan who had a hand in two of his team's three first places. The reliable senior led teammate Keith Chiappa to an easy sweep of the 1000-yard run, finishing just off the Heptagonal record in 2:13.7.

Running the third leg of the two-mile relay, Meehan gave the baton and a twenty-yard lead to anchorman Chiappa, who breezed home for the victory. The time, 7:48.6, established a new Heptagonal mark.

The other Harvard first place came in the afternoon in an expected sweep of the broad jump. Awori repeated his 1963 triumph in the event with a leap of 23 ft., 6 in; Chris Ohiri took second with 23 ft., 4 1/2 in.

But these individual performances, important as they were to the Crimson cause, all faded in the shadow of a world record performance in the 600-yard run by Yale's Wendell Mottley. The senior from Trinidad outdistanced his foes from the starting gun as he sped to the finish in 1:09.2.