M12x1.25 Spark Plug Repair Kit 12 mm This Thread repair kit for M12x1.25 consists of a Special Pilot nose Tap that does not require prior drilling, together with a special insertion tool and 5 off 1.5D Helicoil type inserts (18mm installed length) 2.0D can be supplied if preferred which will have an installed Length of 24mm. Information on Special Tap Supplied Pilot Nose taps have been developed for the repair of damaged sparking plug threads without the need for additional drilling. This type of tap uses the original thread to guide the tap. It has reamer faces behind the pilot thread which cut the hole to size prior to tapping of the wire insert thread form. They are simple and easy to use and in 1 single operation ensure that the wire insert thread is concentrically aligned to the.