Following up a local 'tip' I went to a farm near me today and recovered an M20 engine from the dark recesses of some empty cow stalls..The farmer told me the M20 it had been fitted to was bought by his brother 'some time in the 60's'. When it was no longer serviceable it was scrapped, but they kept the engine in case it 'came in handy for something'.
Well it never did and it was left to moulder in the shippen for the next few decades.
Engine number is WM20 45164 (and Jan might like to know it has one 'B' stamped under the number.)
The crankcases bear some remains of the post war green gloss paint.
A couple of hours after hitting my workshop it was stripped and during that process I came across a modification I have never seen before. As well as the REME magdyno seal housing repair it has had the mag platform repaired in a rather unusual way to remove wear.
A recess has been machined into the platform to level it and a sheet metal plate has been fitted into that to provide a good seat for the mag. The sheet has slots for the pegs on the base of the mag to fit through it and it is retained by two 2BA screws and nuts..the nuts being fitted under the mag platform in the crankcase recess. The heads of the screws fit into the recess in the mag base. Interestingly the plate bridges the crankcase joint so either one or both screws need to be removed to split the crankcases.
The whole job has been very neatly done and I would say is a REME job, particularly as machining of the cases is required to carry it out.
I spoke again to the farmer and he said they had never taken the mag off the bike...
Has anyone seen a similar modification to M20 crankcases?....
Whatever the story it was £30 well spent..
...Ian
email (option): ian@wright52.plus.com
Hi John..it's plastered in old oil, dirt etc..I'll clean it up a bit and take a couple of pics. The timing side crankcase is stamped M54 just below the barrel and has an inspectors stamp V217. I haven't looked up the engine number yet but I think it's about 1941?...Ian
email (option): ian@wright52.plus.com
Glad it's gone to a good home, Ian. Photos of the acceptance markings etc. would be appreciated as they all help to build up a picture that can have practical uses such as pinning down re-stamps.
I expect that the Licensed trade is glad of the £30 that you paid for the lump 'cause the old farmer has probably already got a round in with it accompanied by tales of how he talked a rich collector into paying £30 for five-pounds worth of scrap metal !
Hi Ramon,
We haven't found out what this "B" or "BB" stamps mean. I found them on Royal Enfield engines, and they also appear on BSA engines. Single Bs have also been seen on Matchless crankcases. Is this a silly coincidence? Or is this a military marking? We don't know (yet)... More pictures are needed to find a "pattern"! (If there is one...) 
Cheers,
Jan
email (option): wd.register@gmail.com
We haven't found out what this "B" or "BB" stamps mean. I found them on Royal Enfield engines, and they also appear on BSA engines. Single Bs have also been seen on Matchless crankcases. Is this a silly coincidence? Or is this a military marking? We don't know (yet)... More pictures are needed to find a "pattern"! (If there is one...)
Cheers,
Jan
Jan, dont remember if I told you last week, but all these bikes were classed as "B" vehicles, and early jeeps have a big "B" painted on the dashboard, so could it not be for the fitters to easily identify what they are working on?? or find the relevant parts info etc. etc.
Just an idea.
Cheers,
Lex
email (option): Welbike@welbike.net
Hi Alex..The trouble is it doesn't appear to be stamped on all makes of bikes and there are 'B' and 'BB' stampings...Ian
email (option): ian@wright52.plus.com