>  Or would the faster cooling make the heads crack worse. I do like the
>idea of circulating the coolant after a hot run but only so the engine
>does not heat up more than operating temp just after shut down.  I
>wonder how much hotter the head gets after shut down.

I have a little data on that.  After a several long hard run in hot 
weather with the A/C on the temp. guage runs at about the point where the 
radiator fan switches on (around 85 deg. C?) I have stopped the van after 
a short (30 seconds or so) cooldown.  When I re-started the engine after 
5 minutes or so (you know, the stop for gas in the middle of the desert 
situation), my aftermarket head temperature alarm (which comes on around 
110 C) came on for a few seconds.  I can only assume that it would have 
been even hotter if the starting temperature had been higher or if I had 
switched the engine off immediately.

Bill