[manicmech]

I went a little further than intake gasket replacement, but here goes. I replaced the head gaskets on a '97 Tahoe 5.7. Upon reassembly, I have trouble adjusting the valve lash. I turned engine to TDC of compression stroke for #1 and removed lash so pushrod couldn't be turned. When trying to tighten 1 additional turn, valves begin to open immediately. When I have them where they should be (theoretically), cylinder builds no compression or vacuum. I couldn't find any books referring to another adjustment method. I have successfully used this technique many times on SB Chevy motors before. Am I missing something here?