360 compression

Stock for a 1976 360 2brl is 8.4:1

Is this something you've measured or what the book says it is supposed to be? I have to ask because I've taken apart several 360's (LA's only) and every one was lower than advertised. Some were much lower. The very first one I did opened my eyes to this as it figured out at 7.6 to 1 and it was rated at 8.4 to 1... That's a huge difference.