Especially in air cooled's, fuel is a valve coolant, and that's often the rationale
for funning slightly rich. It's also why it's a good idea to run slightly higher RPM's
driving around town, rather than "lugging" ... more fuel, cooler valves.
bob
On Jun 12, 2011, at 10:26 AM, Ken Wyatt wrote:

> Opps sorry I somehow deleted the results of the second test on a very
> warm engine.  It still failed after freeway driving.  HC was still
> over the max of 220 at 437 PPM versus 469 PPM cold.  CO was 2.83% cold
> and 1.577% warm.  The CO2 on the first test was 12.94% and O2% was
> 1.46% at 2500 RPM.  At Idle it was CO2 at 11.37% and O2 at 2.07 %.  It
> appears we don't check NOx anymore here in Salt Lake.
> 
> I had always heard that the older VW  aircooled engines were designed
> to run slightly rich to enhance engine cooling.  Anyone care to
> comment on that.  My mechanic is an old VW guy from way back and I
> feel he knows the engines.  He completely built it last year with new
> heads and all. So i am having him take the first look at it this week
> while I'm working, hoping its just a small adjustment.  Will report
> back.
> 
> Cheers,
> Ken Wyatt
> 82 westy
> Thinking of mounting my 1976 Lincoln Continental Mark IV's large
> chrome grill onto my 82 Westy, as soon as I add a radiator for the
> 460.  It fits the front vanagon contours well.