Twice now in a short amount of time I have had the porcelain insulator break off and wreck my top end. Both times were with an NGK iridium plug. Any idea what is causing this? Or has anyone heard of this happening to them? Both instances were with different heads. First the s3 with the high high compression head and second time with an RK tek head. Squish is right around 1.2 on both.
https://youtu.be/_I4NOqaBD_g