Tapping noise w/ spark plug pulsating

[Tonyrodz]

Speaking of spare set of heads on the shelf. I was always told by a machinist friend of mine, that when storing heads, to always stand on end and never lay them down flat. Is that still "a thing"?

Just like when storing a crank.

 

[Mudsport96]

Maybe the iron heads if you were worried about trapping moisture in the chambers and getting rust or something... but i also say that is a crankshaft thing.

 

[Rocket Man]

Lmao that plug was dancing all around in that video. If you see that when you start an engine, shut it off before that plug becomes a missile. SMH.