This looks as if it could be a T series Sturmey Archer engine which would have been fitted with a Lucas manual advance/retard magneto however these were troublesome, very expensive to repair and dangerous if not used correctly. For safety and successful running I would fit the later MG2 magneto which has a centrifugal adv/retard and impulse starting aid. Neil Jarrett is the man to source a magneto. I used to own until recently number 137 which was number 36 off the production line from February 1936, do you know the serial number of this machine? If not on the model plate it may be on the front left leg of the engine mount frame or the underside of the gearbox cover.
These engines are very rare as most were replaced with the later TB engine after a number of accidents.

• This reply was modified 3 years, 6 months ago by expeatfarmer.

The engine decompressor mechanism is the main clue and exposed valve gear. I can see that there are some early forged drive wheels amongst the pile. Hope you find the serial number so we can date it.

You may be right but ” starter shaft ” does not look like it has a dog drive , 137 had a similar flywheel/clutch as mine had been broken and I repaired it with heavy washers brazed in, T has a fan drive belt as well as the starter chain drive. Hope he can show more pictures of more bits and a serial number.