Mack donalds

okay thanks for your reply hear me out I found the markings the fly wheel jus needed sanding , but I notice my 1&6 mark are about a couple  degree away from the pointer on the bella housing  when the engine is at tdc or one clutch hole away from the pointer ,what I want to know is do I adjust the valve lash at tdc or work with my markings 1&6 ,2&5, 3&4  and I know that I have to adjust on compression stroke using firing order .(note i took out an injector and incerted a screwdriver in the hole to find tdc )

Hey everyone my name is Donald I work at alescon Trinidad  I'm having a problem with adjusting valves on a mack  I've done it before using the flywheels marks on other mack engines 1&6 etc but I'm working on a 1994  e7 em7 mack engine and sadly the flywheel has no Mark's , took out the injectors and found tdc but someone told me you dont adjust direct at tdc can some one help me out