Andy,
here is the Norton/Matchless P11 website out side of the one here.
https://groups.yahoo.com/neo/groups/norton-p11/info?yguid=463990195
This one (Access Norton) seems to be more active so you can poke around all the different threads in this P11 section.
I didn't write this but here is something I pulled off the internet:
Concerning spacers on P11;
1)Top rear engine plates to frame-spacer located between timing side plate and frame (2 mounting bolts-2spacers)-width-.150
2)Bottom rr. eng. plate to frame-spacer located between timing side plate and frame (2mounting bolts-2 spacers)-width-.150
3)Top trans. bolt-located between trans. case and timing side plate-width.145
4)Bottom trans. bolt-located between trans. case and timing side plate-width-.15
5)Top front engine plate to frame/crankcase bolt-between frame lug and front engine plate timing side-width .150
6)As above,but between plate on drive side and frame lug. width .400
7)Bottom front engine plate-located between frame and drive side engine plate-width-.175
8)Top rear crankcase-located between drive side rear plate and crankcase-width-.350
9)Mid rear crankcase-located between drive side rear plate and crankcase-width-.150
10)Bottom rear crankcase-located between drive side plate and crankcase-width-.160
Hope I didn't miss any! Have 3 of them here and wisely left one assembled for reference.The widths are approximate-from what I can gather they may have varied from bike to bike anyway-at any rate they are within 10 thou. +or-. Hope this helps.-Glenn
You will find the spacer file in the Yahoo but you will have to join to see it and then down load the file. I have the file on my computer. It is just that I don't know how to send it as an attachment.
Cheers,
Thomas