i purchased a 72 z come with a rebuild engine. i recently discovered it is a n42 block with E80 HEAD w/stock cam. my z buddy suggest that im running about 9:1 CR, and it will be running even better with n42 head. lucky i picked up the n42 head from 75 z at the pick a part. right after i removed the head off the engine, i found the 75 N42 block has flat pistons. and then i started to get confused. because my buddy also suggest my 72 z runs on flat top pistons. but not sure of. anyway. didnt any1 run oem N42/N42 w/flat piston combo? and how is the compression ratio on it? thx

 

Best thing would be for you to go download the L Series Engine Calculator from this location: http://www.zcarcreations.com/downloads.htm