Here are my notes from a recent valve adjustment. Hope you find them useful.
I am working on a 08 WRX, 32K KM, AIS still in place, Canadian model. No O2 sensor.
I removed the AIS, coolant tank and pulled away the wiring on the right to make room. This was a fair amount of work, next time I will try and do it w/o pulling away so much, maybe just pulling out the AIS hose will give enough access.
Sparkplug cap didn’t want to come off until I started twisting then came up in my hand.
I didn't touch the throttle body or exhaust, neither were in the way.
Removed the clutch and throttle cables.
To get the cam tensioner out I pulled the starter partway out, there is just enough room with the start twisted against the exhaust to get at the inside tensioner bolt. Just two bolts hold the starter, there is nothing to disengage on the drive end.
I pulled the power cable off the starter, perhaps I didn't need to do this. It was a difficult job as the stud wanted to twist and I couldn't hold it. Since I need to check and lube my swingarm I pulled the shock, this allowed me to hold the starter power lead while loosening. This also makes it easier to get at the inside tensioner bolt. To get at the tensioner bolt with the shock in place you need a very small head ratchet for your 8mm socket. I used screwdriver bit ratchet. A normal ratchet head is too big.
I found in my case the crank mark was about 4mm advanced with the cam marks perfectly horizontal, this would be due to cam chain stretch.
To reset the tensioner I held it down on the bench, pushing down on the body and twisting until the piston was all the way in the body, then, with a small screw driver I could slide the clip over and lock the piston in place.
When you put in the tensioner of course the chain is slack since piston is locked in place. To get the tensioner to release you turn the crank CCW (eng running direction) and it pops out. Not sure of the mechanics of this, I am guessing the chain puts a little tension on the tensioner and clip releases. In any case I had some trouble with this. The reason why is that as you turn the crank the cam lobes eventually go over center and when they do, if the chain is loosr, they jump the chain and you have to start over. I found that holding my hand tight against the chain on the intake cam caused the tensioner to release and no jumping teeth.
-Wes