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Message: <blockquote data-quote="Booboo" data-source="post: 1549033" data-attributes="member: 29137">I did a PI head swap on a NPI short block.   The heads got new stainless steel +1mm valves, bronze guides, BTR springs, new OEM lash adjusters and new "GT supercar performance" followers, cams are XE262AH.    After putting everything back together the engine is down on power.   While tuning we see the expected amount of air going past the MAF but the engine is down on power and commending 30-40% less fuel than it should.   So it appears it is leaking air somewhere.   Compression test shows 185 on every cylider so the cams appear to be degreed correctly.  My thought is that the valve are either too tall or they were installed incorrectly.  Not sure if this is even possible?  When I got the heads back from the machine shop, I notice the valve stems looked funny because they stuck out more than I would have expected. I suspected maybe it was the new lash adjusters so I so I took them out and put in a set of old worn out ones.  The old ones seem to have fixed the problem but at idle only.  I think this backs up my theory that the valve are to tall and the valves are not closing properly.  The lazy lash adjusters are allowing the valves to close at idle (low oil pressure) and when pumped up they hange the valves open.  Is this possible?  Any ideas?</blockquote>