I am going to be upgrading my valve springs soon. The plan is to replace valve springs and retainers with the head still on. I have seen the compressed air method and the rope method are being used.
Are these methods required if I set the cylinder im working on at TDC? Will the valve drop a good amount even when at TDC which is why the air and rope are being used?

Just would like to know if I can get by just setting the piston at TDC when changing the valve springs.

 

I recommend not doing compressed air method. Rope is the safer of the two. But safest is to remove head. TDC is safe for cylinders 1 & 4. Cylinders 2 & 3 will be BDC, so you need to rotate crank 180 degrees to be safe. You can risk it by doing your best to fill 2 & 3 and not rotate. It's tricky to install with head on and not screw up timing belt. GL and don't drop anything small into any of the oil drains.

 

Yea, I plan on doing cylinder 1 and 4 first then rotating to do 2 and 4. Going to be removing the cam gears when cams are removed. By screwing up timing belt do you mean being off on the timing marks? Can I just rotate reverse 180 back to TDC 1 and 4 after finishing 2 and 4 so the timing marks on the bottom end line up, then install cam gears and cams to correct timing marks?

 

If you are trying to avoid having to reset your timing, you need to reinstall gears and timing belt before rotating crank. It's like doing it twice. If you are reinstalling gears to rotate crank, do not reinstall your rockers.

If you plan on resetting timing belt, then you just rotate crank and not have to reinstall gears and belt.

 

Before doing anything, do a compression test to see where you are. If all is good, then install and do a compression test afterwards. Make sure engine is hot and throttle body is fully open when doing compression tests.

 

Line up the timing marks. Paint the belt and onto all the timed sprockets. Pull the belt and cams. Turn the crank anyway you want but don't turn the oil pump. When done with springs put the crank back to its mark, install the cams to their marks, put on the belt and done.

 

Actually, we're not supposed to rotate crabk counterclockwise.

Maybe this is if belt is on.

 

The reasoning for that is the belt might skip a tooth. Here the belt is off so no problem. Manual transmission Subarus have three or four little keepers to prevent this. The idea is that someone parking could tap your bumper - common practice among the senior set. Anyway, no keepers on the 4G63 but I never heard of it happening.

 

Keepers? Aren't those on the valves that hold the retainers in place?

 

I had to look in the manual: Subaru calls them "Timing Belt Guides". One curves over the crank sprocket and three out of four of the cam sprockets also have them, each with slotted holes and two cap screws. It takes more time to install and adjusting these things than it does to replace the belt.

 

Compressed air method works fine, I've done ~15 cam/spring installs that way.

 

I just read this again and that's smart. This way, you just set belt by lining up marks. Should work

 

glad I traded my WRX in for my evo before doing timing belt.

 

If you put the piston at TDC in whichever cylinder you are working, you cannot drop a valve. It's safe to work on each cylinder as long as you have the piston at the top.