what is it? i searched and found nothing. what exactly do they do to o-ring it? why do they o-ring a block? what does it help? thanks

 

helps seal the block and the head better. I know with my GE block, I received thin copper material to guide around each of the cylinders. A groove was cut around each of my cylinders just for the copper wire, which is measured and cut by you unles you have someone else do it for you.