Hi folks,
Was helping get a friends race boat ready for finals and in looking at plugs, we noticed some had been "kissed" by piston domes- first thought was rod bearings as once we saw one, we pulled the plug across from it- same crank journal , sure enough, it was kissed as well on the base/bottom of thread .
Started pulling the rest of the plugs- 4 plugs kissed, others were not across frpm each other- not likely to have lost that many rod bearing with engine good on oil- no noise.
So, I mic'ed the plugs thread length- the four that had kissed pistons were longer- to varying degrees- all the same number NGK race plugs.
Pulled a new box out- these were all closer, but not exact and none as long as the loner ones we had pulled out.

So : FYI, don't trust em- mic em.

Just sayin