Dieseling problem

[Mike Rivers <beatlemikey@yahoo.com>]

Guys,

Been futzing with the Midget this afternoon and can't
keep it from dieseling at shutdown.  I have checked
the timing (12 deg BTDC for a 1969 25D dist), checked
the mixture with Colortune and the idle speed.  Tried
it also with the PCV valve on and off, same thing
happens.  Could it be that the engine isnt quite
broken in yet, or could it be possibly something else
I'm overlooking?

Runs great, except for that.

Mike Rivers 
1961 MG Midget 1275