On Wed, 14 Jan 2009 12:52:18 -0800 (PST), "
wrote:


IOW, concentrating on improving the airflow may be more
helpful than improving the fins.
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Roger that. In spades. Most homebuilt cooling systems aren't. Go
over to AirVW and give a gander at what one of the Monnett's had to
say about VW heads.... and later what he had to say about VW cooling
systems.


I changed some baffles on the O-200 to get around a corrosion problem.
airborne moisture was impacting the fins, blasting off the paint and
then leaving the bare hot steel moisture coated. rust city.

later I noticed some harsh running sounds and while investigating some
oil leaks had the need to replace rocker gaskets.
on one cylinder there was a noticeable build up of carbonised charred
oil on the top of the exhaust valve.
I've since placed a hole in the baffle face to direct air over the
exhaust fins of that cylinder, rather than using the plenum pressure
directed airflow.
The harsh noises have not reoccurred. during the annual in a few
months I'll check for carbon buildup again.

do you find in your vw engines that carbon buildup on the exhaust
valves is any indication of a cooling deficiency?
what indicator do you use for health of a cooling setup?
in other words how can anyone know that they have it right?

in my case oil temps were all totally normal. it seemed to me that the
charred oil was an indicator of a local hot spot that I needed to
address.

Stealth Pilot