I have copied the images from the workshop manual of my LD28. Should SEM448 not be the "Correct" one and SEM449 the "Wrong" one. My logic tells me that if the engine rotates in a clock wise position with the sprocket on the crank being the "driver" and the cam sprocket the "slave" or "follower" in the case where the chain is stretched with Mark B on the sprocket and Mark A is on the static back plate, the "follower" will pass the static mark later.
Reason for this long explanation: my LD28 is not running 100% and my sprocket markings are as per SEM448. How important is the correct position of the marks and does it have a considerable effect on the running of the engine?
This sounds like hot air...but I have had 10 of these cars on the road (mine, my brothers, my parents and a customers cars) starting in late 1986, and have never checked the timing chain stretch. Many of my cars have over 150,000 miles, some over 200,000 and a couple almost 250,000. Including parts cars I have over 20 Maximas with LD28 Diesels.
I believe you will get a lot more increase in power checking the vlave adjustment and especially the injection pump belt. If the belt has 75K to 80K you are getting close. Not many go over 100K. Just put a belt on one car yesterday. Also make sure your fuel filter is clean. If you can mash on the gas pedal and get a fair cloud of black smoke at 50MPH, then you are getting plenty of fuel.
Not to say you are wrong, I can still learn something, but I have never needed to check the cam. It is a bit risky changing the position of the cam gear...if the hydraulic tightener gets out of place, it is tedious getting it back in.
Thank you diesel-man. I rebuilt the enigine new rings bearings Ip etc. Planning to add a turbo (mild boost) once everything is like I want it to be. My LD is in a Nissan Safari/Patrol. Swop from a L28 as it was a almost bolt on, however I later found out is was not the case. Lots of white smoke on initail startup. Discovered after many forwards and backwards that the valve gaps were too tight. Runs much better since.