I have used the compressed air method on a L20B engine. I had to take the cam off. You only need 10-15 lbs of air pressure. Note your crank may rotate.

Originally posted by 280zx Fever

you need to take the head off to do it properly sorry guys but when you push down on the valve spring what happens ! the whole valve moves! and you would need to put something into the cylinder to stop it moving.

Dont bother just replacing the valve stems do it properly the first time.

If you are using the air pressure fitting described in other posts to this thread, the injected air pressure will hold the valve closed just fine. If you insert rope or rubber hose as described in some other posts, the valve will not drop either.

280zx fever- you are absolutely correct- assuming that there are other issues with the head. However, if the goal is to ONLY replace the valve seals (which was my goal, and appearently his), then my and other methods, described here, will work with a lot less headache.

Thanks for your help guys.

i really appreaciate it. i think i'm going to buy a valve spring compresser tool that doesn't require me to remove the cam.

i think i'm going to get the valve seals from autozone, unless someone can tell me they suck. and the full head rebuild will have to wait untill i can afford to do a complete engine overhaul.

thanks again.