Code to modify excerpt length using Bill Erickson's grid loop

separate-excerpts.php

/**
 * Grid Content
 * Change the number of words in excerpt if in the grid loop
 */
function be_grid_content() {
 
  // First, we make sure we're in the grid loop.
	if( ! apply_filters( 'is_genesis_grid_loop', false ) )
		return;
 
	// Change length if teaser
	if( in_array( 'one-half teaser', get_post_class() ) ) {
		$length = 60;
		}
	else {
		$length = 400;
		 //print_r(get_post_class());
}
 
	echo '<p>' . wp_trim_words( get_the_content() , $length ) . '</p>';
	// Remove default content so we don't get both
	 remove_action( 'genesis_post_content', 'genesis_do_post_content' );
}

add_action( 'genesis_post_content', 'be_grid_content', 9 );