are you sure its not a zc? I really don't know much about any of those motors but I believe the zc is a dual overhead cam D-series motor *** edit*** sorry that info was off so I edited it out. I did some searching for you and came across this website.
http://dohc_zc.tripod.com/main.html it has alot of info. The zc came in alot of forms, from SOHC to DOHC, lots of ranges in size and HP etc.