Classic cars forum & vehicle restoration.

[Nic Jarman]

I cannot find the thread about this so here it is.
Pocketing ~verb~ to pocket~ To cause spark to occure within thread space and not in combustion chamber. Generally used in respect of classic cars.
The reason that some cars used short reach plugs in threads that are much longer was so that when the bores and rings were a bit worn and oil would ingress into the combustion chamber it would protect the plug from "oiling up". However this would make a really good combustion impossible and ignition timing critical. There is an answer. I bought some adapters from Pace Products and this converts an 18mm thread to a 10mm thread and a motorbike plug is used. The end of the plug is about flush with the end of the thread as this is very close to the valves, better safe than financially embarrassed.