Review on 🔧 High-Performance W89409 Valve Spring Compressor for Improved Engine Maintenance by Tyler Dorsey

A: The end where the air chuck connector is to attach has an unknown thread pitch. Definitely not a SAE type or metric NPT or AN. You will need to cut the end of the hose and insert a barbed fitting with a female NPT thread. B: I used it on SBF with Victor Jr heads. Spark plug hole 14mm. The 18mm pitch won't fit the head bore and you can't get a wrench on it. C: I ended up resorting to beating the core out of an old spark plug and putting it in an NPT air chuck nipple.