I have a newly rebuilt L28/e88. N42 dish piston block with early e88 head and internally lubricated l28 cam and oversized stainless valves. Motor runs great but after putting about 50 miles on it and getting the valve lash dialed in perfect it has developed a new noise, it is similar to a valve tick but deeper. Originally I was thinking exhaust leak or some chain slap against the guide but couldn't find anything wrong. This morning I finally tracked down the noise after spending about an hour stethescoping the entire engine while running and unfortunately it is coming from the head, it is 100% either the 4th, 5th or 6th cam lobe or corresponding valve, most likely the 5th lobe which is the intake valve on the 3rd cylinder. The noise is noticeably louder after the engine is fully warmed up but it does not get louder with rpms, after 1200-1500rpm the engine is loud enough to drown the noise out but it is very, very noticeable at idle now and sounds like its getting progressively louder to me at this point. Lash has been adjusted with the engine fully warmed up to .10i and .12e and triple checked, it is perfect. The only thing visually different about the 5th cam lobe is a little uneven corner wear, but wtching during rotation this wear does not contact the rocker lash pad, so I guess it was there prior to the rebuild...the other 4th and 6th lobes look normal. Anyone have any opinions, advice or ideas?