Spark Plug terminal nuts

[The Bishop]

This isn't VW specific but I am hoping someone intelligent can explain,

I have a two stroke engine which is fitted with a Spark Plug Cap that fits the thread on a spark plug. being a small engine there seems to be a breakdown of the metal where the cap fits over time and when it gets too loose I replace the plug. I was thinking of changing the cap to one that fits onto the nut that usually comes with pugs so that there is a bigger connection and less prone to erosion.

Why do some engines use the threaded connection and some the ferule/nut connection? Are there advantages/disadvantages of each? It seems high revving engines seem to use the thread more?

[California Dreamin]

Older Din fitting (using the screw on cap) newer 'Pin type' fixing to the smaller threaded center electrode.....if I'm honest I think the smaller threaded type are more secure.

Martin

[G Dub52]

I always wondered that but never asked, now i know