Experimental Department - Engine Development ED

[halpiboy]

Hi guys, I'm wondering if anyone would know of records from the BSA Experimental Department at all. I have a A10 twin engine (stamped ED.171). I'm wondering is there are any records around the ED numbering, i.e. what was specific about this engine and if there are any details around testing.

[BritTwit]

Interesting.  A few things to consider:

Thin flange cylinder
ED. font different from 171
I think? the experimental dept. projects were stamped EX (just my opinion)
Check the right side case (dynamo area) for a date code stamping (small font).

[halpiboy]

It looks like the ED donations were assigned, then numerically stamped later (once utilised within the Experimental Department). As per the A50R sold at Bonhams, which was a special out of the Experimental Department, both the frame and engine ED xxx are of differing stamp sizes indicating parts were assigned for use then stamped once utilised.

https://www.bonhams.com/auctions/20469/lot/381A/

Shall have a look for a date stamping, the other point was the entire engine is matt black finished 

[Sluggo]

I have no idea personally but thank you for bringing attention to it.  I *LOVE* that BSA A50 racer you linked to, was not aware of it before and very cool.  (I have some unit A65s and singles so a cool bike like that is great to see)
Not to hijack your thread but I found it super interesting that A50 ran a Magneto off the back of the timing case. Did not think that was possible. (Would love to see some internal engine details on that)
I would THINK you should be contacting the BSAOC and see if there is records of your engine, Be very interesting to see what turns up.
Have you read the material from Val Pages autobiography?  It appears he was not a big fan of the twins. (Goldstar man) but he was tasked with engineering and process improvements on them which led to eventual great success.  Perhaps your motor is a later test piece.

[BSA_54A10]

Usually numbers ooo through to 100 were used for experimenting and factory race specials which is why BSA numbers started from 101.
However BSA engines were also used in small cars and other weird & wonderful devices of the 50's & 60's so without any sort of providence, we would be guessing.