I found these thread adaptors, you think they could be used for the purpose?

Click on the Technical tab:
http://www.walraven.com/gb/en/catalogue ... tegory_500

Don't see why not. Just use a bit of PTFE tape on the thread of your stem when you screw it into the adapter.

Seems like it will do the job.

I dont have a 30 spark plug to measure, just need to make sure the pitch is correct else it wont screw in.

i.e. an M10 size hole can have 1.25 / 1.5 or 1.0 pitch.

Needs to match the plug

It says M8 and M10. M8 can be 1 or 1.25mm pitch. Would be nice to know what's the thread pitch of 8mm and 10mm sparkplugs...

Try this then! :-)

1mm for E type plugs, unless I'm mistaken.

http://ngkntk.co.uk/wp-content/uploads/ ... le-Cat.pdf

This tittibird tells me the E in ER9EH means it's an 8mm plug with a 1mm pitch. She also says that 10mm plugs come with 1mm pich as well. M8 and M10 coarse is 1.25 and 1.5 pitch, since the default thread pitch is coarse so that adaptor wont work.
http://www.google.com/url?sa=t&rct=j&q= ... OrVS9Qg0hA

What would be the simplest way to make a M8x19mm male to M10 female adaptor in fine pitch with a 13mm hex head and possible a recess for a sealing o-ring?

Well, if I had a lathe, some 13mm hex bar, and the appropriate cutting tools... lol

Cant you just cut down an old plug and tap the inside to watever thread you adapter is( or solder something on)? Thats what i usually do!
Cheers
Ian

That sounds like a pretty sensible idea!

Morespeedvicar wrote:Cant you just cut down an old plug and tap the inside to watever thread you adapter is( or solder something on)? Thats what i usually do!
Cheers
Ian

How to disembowel them?