Wasn't sure if this should go into Second Gen forums or here but since these are the technical forums...
SHORT VERSION: Can the valve buckets in a 96 EJ25D head be replaced with shim-over-buckets from a 99 EJ25D head? What needs to go with them, such as cams, valve seats, etc? Would they have to be re-shimmed? Would it be easier/safer to just transplant valves into the 99 heads?
Have a 96 LGT. Just got to tearing the engine down after what I thought was a timing jump. Turns out I blew out the bearing in the toothed timing idler pulley. Car shut down immediately. Somehow, and we are still confused by this luck... It looks like I didn't actually have a valve collision. Do not ask... I don't know. We're guessing all my cams jumped to a "safe" closed position at the right time because there was essentially no pressure on the cam sprockets from the belt.
Why am I worried about the valves? My valve buckets are mixed up. And putting them back in wrong can lead to some very serious problems from what I'm told.
The 96 EJ25D has HLA heads (buckets) designed to run on 91+ octane. The 97-99 heads are shim-over -bucket style and are lower compression and designed for 87 octane. The latter does make a bit more power though. Hopefully you already know this if you're going to give advice though. =)
The heads are normally at least $200+ each and I do not have much cash to fix this. I found a set from a 99 outback (also phase I) on nasioc that "needed new valves" for free, but I gave the guy $50 for them because he held onto them for me.
I've been told that the later heads will run just fine on my car with my 1996 ECU. I put the heads cam-side-down about an hour ago and filled the tops with ATF to check if the valves were seating/bent. My friend who is helping me said this is a pretty definitive test for bent valves. If they don't leak over 24 hours, the only test more comprehensive is a pressure test. He said I should be able to tell within 6 hours though.
What I've found so far is that at least 12 out of 16 valves on the "new" heads are leaking out of the intake/exhaust ports (or cant be trusted because they are next to a leaking valve). My plan was to replace whatever valves I needed on the new heads with good valves from my old head. Now it's looking like all of my old valves are just fine and maybe I should change out the buckets/put in shim-over-buckets if that's possible.
What would you say is the easiest/cheapest way to make good heads? I am starting to think it might be cheaper to order new buckets and keep my old heads.
Following up: my heads turned out to be fine, all valves seating. New heads were jacked. Sticking with my HLA's. Thanks all!