Hitchcocks Forum

Hi, I have to repair a spark plug thread on a crusader. Does anyone know what size helicoil i should get?

14mm

Our hosts do them on page 272 of the current cat. OR.... you might try this for a "Quickie" repair}---https://www.amazon.co.uk/14mm-Spark-Plu ... oding=UTF8& ------

Thanks lads. I bought a 14mm kit but it's too big! So I assume it's 12mm??? Anyone used one??

14mm is the correct size.

NGK B6HS is the plug for the crusader and it's a 14 mm thread.
Your insert is 14mm on the inside.
You have to drill and tap your plug hole to the outside size of your insert.
Good kits usually come with the correct drill and tap plus insert insertion tool. Best of luck.

As everyone says 14mm is correct. Are you looking at the OD of the insert? That will be larger than 14mm. But the correct thread size once fitted must be 14mm - unless someone somewhere sometime has modified this 60 odd year old engine.

Just a thought, if the original thread was getting tired someone could have fitted a 12mm insert which is pretty close to 14mm on the outside??

Just as a follow-on from HAGGIS, what plug have you removed from the head ??.... Can you post a photo ?....

Maybe Dutto could reach for a measuring tool and measure the thread diameter of the spark plug for himself - just a thought!