At 8:57 AM -0700 8/17/98, Harmon Seaver wrote:
>Just got a pair of rebuilt heads for my '81 2.0L from BusDepot, they
>look good and came quick. However, one has a pair of cylinder shims and
>a pair of head shims -- the other has just a pair of cylinder shims and
>a note *NOT* to use head shims.
>    I'm a bit confused. Don't have a Bentley for this engine, only a
>Haines, but it talks about "sealing rings" on the heads. So is the head
>shim in addition to the sealing rings from the gasket set? Seems like
>that wouldn't give the greatest seal. OTOH, the earlier air-cooled
>engines had no head gasket at all, and they did fine.

From: David Schwarze <des@tiu.net>
>The type IV engine was originally designed to use the ring gaskets, but
>sometime after that VW, or perhaps one of the rebuilders, started
>recommending against using them.  I can't imagine why.  I have always used
>them and will continue to do so, rather than take the risk of omitting them
>and losing compression due to a leak.  My engine has enough miles on it now
>that I am confident that running them does no harm.  As always, YMMV, but
>that's my say on the matter.

From what I've been told, VW issued a service bulletin which stated that
the head gaskets were NOT to be used.  The cylinder shims where then
used to set the deck height and keep the compression ratio correct.  I
suspect that it has to do with the configuration of the head bolts on
these engines.  If you look at how they surround the piston, they are
spaced in the shape of a rectangle rather square (as in type 1 heads).
Apparently, by removing the head gasket allows the heads to seat deeper
on the cylinder and gives a better seal.

Scott
http://www.dolphinsci.com/typeIV.html
http://www.dolphinsci.com/crewcab.html