[pat in Santa Cruz]

I have lion #13. It must be lucky 13. It did ping at first, due to the plug threads being extended too far into the combustion chamber. They acted like glow plugs. I ground the threads off below the tip of the spark plug, and sanded the sharp corners smooth ( not the edge that bites into the gasket). No more pinging. The head tolerates a lot of advance, its powerful and very smooth. The same engine with a Brumfield shaved to 7:1 is rough, tho' quite strong and tolerates only about 20 degrees advance.