Firstly the question."What do i do if a spark plug is threaded"?
Answer "Screw it in," all plugs are threaded.
Surely you meant cross threaded.
Was the plug tight coming out?
If not it should not be tight going back.
It is very easy to cross thread a plug refitting it, if the plug was tight coming out before refitting the threads should be cleaned with a wire brush and smeared with a small amount of copper grease. On refitting, the plug should be hand engaged in the head and screwed in a few turn by hand. NEVER try to engage a plug with the socket attached to the ratchet. To engage plugs in tight situations, get a short piece of rubber hose and push it over the plug insulator, use that to hand engage the plugs. The tool mention above whilst with very careful application CAN be used to realign slightly crossed threads it is not mean for that purpose. It is design to CLEAN good threads removing any carbon build up from the lower thread. If the start of the thread has been damaged use of this tool requires great care and correct alignment in order not to permanently damage the rest of the thread. Incorrect use of this tool could strip the rest of the thread. As Irish says a little grease applied to tool will catch most of the swarf.
