Hey Rob

I use the Nelson Plug, I obtained a Galbreath head that did not have the combustion chamber cut into it.
I cut a chamber using a .312 ball end mill in the tailstock of a lathe. I did not use the stock head gasket that came with the ap, it was .008 thick. I used one .002 norvel gasket. I cut the case/cyl face down to give me a .008 deck using the .002 gasket. Along with my other mods, this engine setled in at a little over 30k on 40% fuel. I have ran 12oz of fuel through it so far, I have not mounted it on one of my planes and flown it yet. I have been busy doing other model things latly. I will let you know how consistant it is set up like I do my VA's or Norvels. So far, it looks like it will be a bit on the weaker side in comparison. I wish the piston/cyl fit was a bit tighter.