I have 1999 Subaru Forester with a SOHC/Ej25 that had an apparent engine knock. I replaced the block with a known good replacement, and experienced the same sound, so I replaced the block with another known good low mile block with the same results.
I have 2 blocks that are known to be in good condition and the original with an unknown history, all are making what sounds like a rod knock, but I find it hard to believe that it is. Every assembly was assembled using the original heads, new head gaskets, and new timing components. I have checked the vaulves, and they appear to be well within the specifications. So I strongly believe that they are not making the noise, and it does'nt sound like vaulve noise in the first place. Any ideas from the community would be appreciated.