Dumb Sparkplug Question

[Jandrews]

I just bought a new set of NGK's and I was taking a look at them while watching TV tonight. One question occurred to me... what is the purpose of the screw on/off tips? There was some kind of instructional graphic on the NGK box referring to these ends, but I couldn't make out the point it was trying to make.

Any help would be appreciated.

Thanks,

JA

[unclebilly]

Some vehicles have spark plug leads that do not accomidate the bigger diameter screw off ends. Motor cycles for instance and old Model T's both use the smaller diameter tip. Motor cycle leads slide on the same way as the normal car stuff, the leads on model T's are connected to the plug with a nut.

[Early_S_Man]

Here is a complete reference on ignition connector systems, including the M4 threads used by air-cooled VW and 356s on their spark plug connectors:

http://www.beru.com/download/produkte/stecker-TI05_e.pdf