: engine itself. In fact I think the EGT rise is a direct consequence
: of the CHT reduction although I can't quite remember how that
: connection is made.

One plug not firing will slow the combustion event, resulting in the burning
mixture exiting via the open exhaust valve. Results in higher EGT with a
lower CHT because the heat escapes instead of being converted to work
in the cylinder.
--
Aaron Coolidge