Not full article in the index

Thank you very much, but I still have a problem. this function is limited to 55 words. I need to expand it to 200 words. I added to my functions file:

function custom_excerpt_length( $length ) {
	return 20;
}
add_filter( 'excerpt_length', 'custom_excerpt_length', 200 );

But its still same – 55.
why?