To get the most out of your water cooled 1.9 liter motor, try changing the
ignition timing to 8 degrees before tdc or 35 degrees full advance.
My van is a whole different beast.
 Better acceleration better power band, seems to run cooler and mileage is
around 18 mpg for a Westy 85'

I've had my van like this for a year now and the van  loves the setting.