I have been considering this modification for some time, and today I located the aluminium heat sink-radiator material which I needed, and which I knew was somewhere in my stuff.
The Koffiekop Sirling engine requires differential temperatures between the top and bottom plates. I wondered if installing some heat shedding plates on the top plate might increase the running time on a cup of coffee.
Afterwards I ran a test with a cup of hot water.
The engine ran for 26 minutes! That is an improvement of about 25% on the best previous runs. Success!
The Horizontal Mill Engine (HME) is assembled and ready for the D valve to be timed. This is how it looks. I wont get to it for a couple of weeks now.