Hi Bart,
I'm still contemplating just how to measure the difference...First, I would like to run this engine as is to see just where the CHTs are in stock form..I was thinking of making a stand, adding a direct drive prop, and then measuring the thrust{and watching the CHTs} as each mod is made..
I know papee stated he gained 500 rpm just doing the carb swap with the DD prop..So breaking out of a props usable range could be a real factor..
Knowing now how critical those head temps are I'm going to NOT paint the heads or jugs..There's a few coatings I have in mind that will keep the rust at bay but not hinder the cooling ability of the fins..
The combustion chamber coating is definitely something I want to look into..
As far as the heads themselves go I want to look into the ports and see just what we've got and if any massaging would expedite the flow to move the heat..
I'm waiting to see how your piston oiling mods go for cooling...