Great when a plan comes together, I take it no drilling involved it's just an oversize M10 tap? So you screw the insert directly onto the spark plug and then screw the spark plug into the head hope I've got this correct?
Great when a plan comes together, I take it no drilling involved it's just an oversize M10 tap? So you screw the insert directly onto the spark plug and then screw the spark plug into the head hope I've got this correct?
The insert and tap is m12 x 1 the drill size for which is 11mm. Sods law says I couldn't find an 11mm bit when I needed one but so used a 27/64" (10.7mm) drill instead it was a bit tight tapping the thread but the aluminium was so soft it went ok. Some of the more expensive regulator kits come with a stepped tap so no drilling required. If you are patient I suspect you could just use the tapered nose of the tap to ream out the original 10mm plug hole until it was large enough to allow the tap to start cutting the thread.
As for fitting the insert I smothered the thread in permanent thread lock and wound it in as far as possible with my fingers then just tightened it up by winding in the plug.