\renewcommand\section{\@startsection {section}{1}{\z@}%
{-3.5ex \@plus -1ex \@minus -.2ex}%
{2.3ex \@plus .2ex}%
- {\@acmtitlestyle}}
+ {\@acmtitlestyle\Large}}
\renewcommand\subsection{\@startsection{subsection}{2}{\z@}%
{-3.25ex \@plus -1ex \@minus -.2ex}%
{1.5ex \@plus .2ex}%