Originally Posted by Caballerokid
Hopefully these are larger pictures. Also... these were after 3 hard pulls on the dyno with a 160 degree thermostat. I want to go to a 180 thermostat. Would I need to go down to maybe an R43TS?
When you see one side of a plug colored much more than the other, chances are good that if you were to index the plug to tell what valve the colored side was pointing towards, it would be the exhaust valve.
You can mark the position of the colored half of the insulator on the outside of the plug w/a sharpie, then screw the plug back in the head (same plug/same hole it was in). Note the position of the witness mark you made, it'll be biased towards one of the two valves.
Reading spark plugs
based on the Odom text, you can basically ignore the General spark plug info section below the info on reading plugs.