AAU Shroud?

[trevinoz]

A friend has this shroud which appears to fit an AAU.
I have never seen or heard of this. I cannot see the need for it but it may have been fitted to something other than a BSA.
Anyone know of it?

[CheeserBeezer]

ATD's were being manufactured in the UK by an independent firm until a few years ago. I believe this firm made them with the cover of the type you have. I'm not aware of Lucas making covers for any of their ATD's. Maybe the cover is to prevent bits falling into the timing chest if the ATD flies apart?

[JulianS]

I think the shroud was a feature of early ATDs as fitted to the long stroke A7. Below is from a contemporary magazine review of the long stroke engine and shows a shrouded ATD.

Of course it would be difficult to set the unit to full advance by wedging the weights as normal for timing because of the shroud.

The early Long stroke timing was given as a retarded setting.

[trevinoz]

Thanks Julian, that looks exactly like the shroud pictured,

[Swarfcut]

   Thanks Julian, for that insight from way back when. Mr Perkins is the man who made life difficult with his rocker box idea, certainly easier on the Longstroke, not so with the one piece box. They saw sense later on with the Unit models.

    Still, the below the line comments make interesting reading, nothing changes as they big up simple engineering concepts.

 The engine illustrated is the very early type...only two bolts at the bottom of the timing cover. Later have three. Be aware of this if you are looking for bits. Later Crankcase and both timing covers are different castings from this version.

 Swarfy.