General Plug reading Rules:
1.You set your heat range from the ground strap (this is the piece closest to the piston).
2. You can do all the plug reading for jetting from the base ring (the base ring is what the ground strap is welded
3. You determine detonation and timing issues from the porcelain. The porcelain shows pre-ignition/detonation
and will not accurately determine jetting/air/fuel ratios. DO NOT BASE JETTING DECISIONS ON THE PORCELAIN