sm blk X and J heads

I don't know why you'd change the spark plug to CC a chamber. The chamber has the spark plug installed when it's running. Your way is wasting time. The total volume of the chamber includes the spark plug you run.
Your post was a waste of time. I pointed that out in my reply, the difference between actual cc of the head...and running cc aka with spark plug. I've seen oily plugs used and air pockets in the crevices. If one was to build and modify a set of heads for sale, he could correct the chambers to a specific cc either way he wanted, no matter what you say...I know, omg, what are you gonna do??
Nothing wrong with having chamber checking plug laying around, switch heat ranges and the plug gets smaller...omg what now??
Stop nit picking.