This post is regarding cam timing and cam sprockets.
Sooner or later any DIY mechanic will need to change the timing belt and VVT sprocket/sprockets.
There are tons of how-to procedures out there explaining how to do this, and I've
also got the VADIS procedure, but non of these answers the million dollar question
most people encounter when they're unpacking the new VVT-sprocket and finds out
there's no keyway or markings to aid in how to put the new sprocket back on the camshaft.
This post is an attempt to settle this question once and for all, since there's no way
I'm going to pull parts and then not knowing exactly how to put them back on.

Let me start by explaining how I think it's done and then please comment to either confirm or
correct what I'm saying.

My engine is the B4148S2, 1.8 litre, non turbo, non GDI with a VVT sprocket on the intake cam.
There are two kinds of sprockets in circulation: One with a helix-gear and spring, and one with
a locking pin and vanes. Mine is the version with the locking pin and vanes.

Let's say I've made it so far as to remove all parts needed to gain access to everything.
I've got the crank locking tool and the cam locking tool ready.
After inserting the crank locking tool into the hole behind the starter motor I know that the
crank is in the correct position, no doubt about it.
Now the cams should also be correctly aligned with the crank provided the previous owner or a
workshop mechanic or timing belt slip/wear hasn't messed things up.
Now I remove the timing belt.
There is a procedure to check wether the cams are correctly aligned or not, let's say I've
followed this procedure and now it's time to insert the cam locking tool.
Now the crank/cam timing is correct no matter what previously made markings on the cam sprockets
may tell you. As stated before, you never know what people or wear/belt slip may have done to the
alignment.

Now it's time to pull the VVT-sprocket.

Looking at the new VVT-sprocket there is no keyway, nor are there markings on it.
Not even a hint of a mark in the engine block either, just two small low accuracy notches on the plastic timing
sprocket cover. -Why?
Are the engineers at Volvo morons? There must be a logical reason for the total lack of alignement
marks or keyways, and the reason is they're not needed.
They're not needed simply because the engineers at Volvo counts on the mechanic using the correct tools
for the job;-the crank and cam locking tools.

You can put the VVT-sprocket on as you wish, provided you torque it down just so that it's able to rotate
slightly when the timing belt is tensioned using the correct tensioning procedure.
After the timing belt is tensioned the VVT-sprocket is torqued down with the correct value.
The idea is that the timing belt must have the same tension all around, so that when you remove the cam locking tool
there is no uneven tension on any section of the belt to cause the cam shafts to change alignement once the locking tool is removed.

As I said before, please confirm or correct my understanding of how this works. I can see no other reason for why
Volvo has no keyways or markings than that such markings are simply not needed.