I would say a 5/8" plug socket. If you have one,that hasnt got the rubber insert in the socket,to hold the spark plug when you remove it out of the head,loosen the plug and then get a clean peice of garden hose and slip that over the end of the plug and unscrew it that way.
Removed the champions in mine with a 5/8" socket,but the new NGK's need a 11/16" socket,anyone know why?
No idea Are you sure you have the correct cross referenced plug?Champion to NGK? Maybe because they are made by different company's? As long as the NGK's wind in and have the same sealing surface and have the same reach as the old champions,then it doesnt really matter.
Sealing surface looks the same,reach is the same,cross reference is right. Think I'm just pissed that I haven't got an 11/16" plugsocket,not a well used size over here for plugs.
