timing chain install (long)
I've pulled 2 valve covers in the last 2 weeks on Z24 single cam motors, and neither one had any markings other than a single dot (no number, either). Before you go spinning a cam around to get to #1, make sure that none of the pistons are at TDC lest you ding a valve.... The alternative is to install the cam with the rockers out - that way it's easy to turn the cam.
Having found at least a dozen "slipped" dampers (that otherwise look fine) in the last 20 years, before I pull any motor apart, I always check to make sure that TDC on the pulley is REALLY at TDC. Insert a very thin long blade screwdriver into #1 at a fairly steep angle with all 4 plugs out. Slowly turn the motor until the cam keyway begins to point upward (approaching #1 TDC) . Find the piston top with the screwdriver blade (don't let it wedge between piston top or bore and the hole) and carefully rotate the crank while holding slight pressure against the blade until you feel the blade go "over the top" and begin to fall back down a tiny bit. Roll the engine back and forth just enough to find the spot where the screwdriver stops moving at the exact top of the travel.
If the TDC marker on the crank pulley is not exactly centered on the pointer when the screwdriver is exactly at the top of the piston travel (and you are positive that the piston is at TDC) then make a new TDC reference mark and index the rest of the marks the same amount. If it's more than about 1/8" off from the existing mark, then the pulley may have rotated in the rubber damper ring and should be replaced (or at least kept watch on by painting a thin white stripe across the face - if it moves. you'll see a zigzag in the stripe.
Reassembly - with the cam's keyway pointing pretty much straight up, bring the crank around to TDC. If you leave the rockers installed, there is no chance of bending a valve. If you remove the rockers, you should at have a couple of upper cam journals snugged down but not torqued, using spacers, to keep the cam from moving off the bottom journals.
Once you have the crank and cam at TDC (as shown) install the crank and cam sprockets together with the chain as a single unit, worrying the chain around the tensioner. You should have the shiny link lined up as illustrated, but some cheapo chains don't have a "#1"link (mine had a tiny dot on it that was very hard to see). Also, my aftermarket camgear only had one dot on it. Paint the link that matches up to the dot (with the arrow) with nail polish or flat white paint, and once everything is in place, snug up the cam bolt and slide the damper on and rotate the engine very slowly (plugs out) 360*
The shiny or painted link indicated on the arrow should be installed so that it exactly matches the arrow in the illustration that shows a slightly darker link. It may take a few times to get the package in the right position, but it will go together exactly as illustrated.
When the cam and crank are back to where they belong, and the link still matches up, then pull the crank damper, slide the front cover over the crank and line it up with a couple bolts then check the pulley marks against the #1 timing mark, and the painted link against the dot. When there is no oil pressure against the tensioner, a loose chain can jump if you turn the motor too far against the direction of travel. I wedge a hard nylon "glass tool" against the tensioner so that I know it won't release tension. Try one last time to be certain that the timing is exactly right, using the screwdriver at to make sure that you are at TDC when everything comes around and lines up. This procedure basically works for anything from a 2.4 Nissan to a 4 cam Ferrari, it's just a lot quicker on the Nissan, and is far easier to do than to explain. At least the second time around