Quad Polsten spark plug?

[Richard Farrant]

Originally posted by Richard Notton
you have a 14mm thread of about 10mm length, taper seat and short insulator. This would equate to a BM6F I think.

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.

Tyler, go to www.gsparkplug.com and with info I posted to your request on HMVF forum, you will see that the British Champion equivalent from my 1951 KLG book was 17. The Green Spark Plug Co. website shows 17 to be now superceded to D9 which has a copper core, available of the shelf at a few pounds.

Richard