By noon today New York City will be firmly in the grip of the season's most torrid heat wave--generated by the American Legion's Societe des Quarante et Huit Chevaux, official custodians of the huge quantity of fun and frolic that is to be showered on the convention of some 200,000 Legionnaires. Only blue-nosed New Yorkers--if such there be--will resent the audible expressions of good, clean fun, and by the time the last Legionnaire entrains for home, New York will have forgotten just who was making all the noise.

But the less tangible results of the Legion convention will not be so easily passed over. The Legion has long had the reputation of being the most conservative--some would say reactionary--of veteran organizations. While it has performed many charitable and civic services, it has never seen accused of putting the interests of the nation before those of the veteran. At every level of government from Washington to the ward, it is a vociferous and effective pressure group.

After the influx of returning World War II veterans, it was hoped that the historic policies of the Legion would be modified to reflect the views of its junior partners, who were considered somewhat less hidebound than the old guard. But so far the hierarchy has held firm. The opinions it expresses, and which are given close attention in Congress, are not and do not pretend to be those of a majority of veterans or even Legionnaires. Rather policies are formulated at the top and passed down to the membership.

A strong element in the Legion says things are going to be different this year. The position of National Commander, usually filled unanimously by a hand-picked candidate, is to be the focal point of a wide open free-for-all. If the rebellious group is able to "un-can" the convention and make a bid for the top post, it may open the way for making the Legion a really democratic organization, a development which would be salutary for both the Legion and the nation.