Hi all,
I've been wanting to thank Bob Donalds from Boston Engine
for enlightening us about the hydr. valve lifter preload issue.

This is what happened to me recently: After an upper engine rebuild on my
2.1 liter wbx. The work included: New German made cylinder heads,
(bought them some years back and had them ceramic coated),
new Mahle piston kit, and new oem. hydr.lifters, and replacing all the
cylinder head studs and oil pump for good measure.
The shop I chose to do the work likes to go by the book, that's why I had
them do the job in the first place. After the rebuild I tried to get them
to adjust the valve/hydr.lifter clearance as Bob described.
The shop-owner refused, since he only goes by VW specifications,
and never received a VW bulletin on this subject.
(Owner is a certified Audi mechanic, and they have done many rebuilds
on vanagons, and stand behind their work with a 12 month warranty).
All worked out quite well. They put the motor back together, and it runs
beautiful. I changed the oil after 100 miles, then again at 500 miles.
At 1000 miles, I installed 20/50 reg. oil, and did a compression test.
This is what I got: (engine hot, crank for 3 sec)
Nr.1  135   Nr.2  160   Nr.3  140   Nr.4  160
So I took off the valve covers, and readjusted all the lifters per Bentley,
except for the 2 turn preload.
Basically I backed off the adjusting screws, and then turned them back in
by hand till they made slight contact and tightened them in that position.
 (engine slightly warm)
After driving a couple hundred miles, I did another compression test.
This is what I got now.
 (engine hot, crank for 3 sec)
Nr.1  160   Nr.2  160   Nr.3  163   Nr.4   160
Much much better. Biggest surprise was, that even with 0 preload on the
lifters, the engine runs as quiet as before. There is no increase in valve
lifter noise whatsoever, and there appears to be more power
when climbing hills.
Harald
90 westy