Just did a compression test and two cylinders were low @ 100 and 106.
Heads done about 20,000 miles ago by a VW mechanic (not dealer).  Van
has ran pretty well since them but lately I have developed a lumpy
idle and low manifold vacuum (10-12).  I researched everything I
could find on the age old valve lifter issue including a call to Bob
at Boston Engine were I purchased my heads from.  Followed his
instructions and adjusted the valves to .006 inch valve lash.  I
adjusted both intake and exhaust when engine cold.  Just to be really
thorough I rechecked them almost immediately after I adjusted them
(did not rotate the crank yet) and I swear I was back to zero
clearance so I readjusted again but did not recheck again cause i
wanted to finish and the mosquitos were really bad last nite.  I also
checked all the valves for clearance before I adjusted and I could
not get a .006 inch feeler gauge in on any of them--I am suspected my
mechanic may of installed these heads the old way (preloading) and I
am starting to see problems  now.  My question is why did I lose this
.006 inch clearance just moments after I made the adjustment?

I did start the engine up after adjusting all the valves and it ran
pretty much the same, initially the manifold vacuum was about 14 but
then dropped to 11-12 after the engine warmed up and idle was lumpy.

Could it be the lifters are doing something strange?  I am running
20W-50 for the summer.

Tim
--