Has he tried cooler spark plugs and retarding the ignition timing? Is the
cooling system working properly? Sometimes the return loop in the engine
compartment will clog where the small hoses from the heads connect.
Especially that hose near the AC compressor, (cylinder #4). When coolant
can't flow through those hoses the heads will get hot near the one cylinder
and cause pinging.

I personally think the modified engine is just a bad idea. VW detuned this
engine for a number of reasons. A lot of thought went into the dished
pistons, low compression ratio, and moderate ignition timing for a number of
reasons. Pollution concerns (NOx) and the ability to run at open throttle
without melting pistons was the obvious focus. The next diagnosis is to
confirm that it is really knock and not piston slap. BTDT!

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Ian Allan
Sent: Tuesday, September 15, 2009 11:05 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 2.1 heads

I have a friend who purchased a van with a Go Westy 2.4 engine. The
engine has suffered from detonation issues among other things. Any
ideas as to practical machining processes to REDUCE the compression
ratio?

Ian