It's gear driven mate with pushrods one of the best nissan motors ever, got 500.000 out of mine when i traded still like new also go to d21 section of the forum probably get more info there
Sorry mate i carn't help you that motor is now 25yrs old in the day it was the slowest but the most reliable i have no idea where you will find a manual but as i said before go to the d21 section surely there are some owners there after all if it wasn't for the the d21 this forum would not exist all the best