|It works! That propeller is an 16 x 8 Master Airscrew|
After a lot of thinking and research on the internet I thought that the fuel was not burning correctly. I've put it down to the glow plugs not protruding far enough into the combustion chamber so I've made the plug recess 2.3mm deeper on the outside.
|Seems to be more reliable and controllable with two carbs.|