Quad Polsten spark plug?

Originally posted by Richard Farrant
The Champion 6-M was a US made plug, I looked it up in a very old KLG book and it equates to a KLG M30. This plug is an 18mm thread with a reach of 12.5mm, not taper seated either, just conventional washer type.

The problem of not having a scale to the picture!

That's a NGK AB2, somewhat odd in having a smaller hex than usual and being a very soft plug. Available from the net, eg:
http://www.camskill.co.uk/products.p...8b16s1221p4345


R.