Norvel V Max .061

I bought 4 Norvel .061 V-Max engines some time ago.  I really purchased them for spare cylinders for my combat engines. After closely looking at the engine, a few things looked beneficial such as the venturi stack. I figured this could stop the dirt ingesting. Unfortunately, it sticks out so far that flipping a prop is problematic. I shaved it down a bit. The needle appeared to be fairly fine with a decent taper. This didn't work on pressure so I installed a fine F2D version. I had to make a prop driver as this engine didn't come with one as it was designed for a helicopter. The engine also came with a large heat sink head. I removed that and installed my Galbreath/Nelson head. I tried to fly combat with one and the other was also a Norvel .061 that I've been using for some time. The older proven engine well broken in is achieving 29K no problems. The new V Max was hitting 22K. Hmmm, I looked deeper into the engine taking it apart numerous times. Well, tonight I discovered the issue. There's a bit of a landing on the cylinder which I believe is there to support the stock large heatsink head. The Nelson head was bottoming out on this before seating on the plug landing. I used a Merlin head clamp with a Norvel plug and the engine fired right up and hit 30K+. I shut it down and will be hoping for success tomorrow. So for anyone who's experienced a similar problem, keep that in mind.