HeliCoil 5396-14 Sav-A-Thread HT - Ford 5.4 and 4.6 Liter Spark Plug Thread Repair M14 x 1.25 spark plug thread repair Designed for -Inch Half Thread-Inch (HT) spark plug applications in 4.6 and 5.4 liter engines Allows access to deep ports Positive mechanical locking feature ensures insert stability; insert will not come out Utilizing the piloted reamer tap, alignment is maintained and pre-drilling is not required. Note: It is recommended that the head be removed before installation to ensure chips do not enter the cylinder