Among a recent job lot of Longstroke bits is this follower, which looks the right part but isn't.
Standard follower is 75.7 mm long, this mystery is 76.9mm. Also the ball tip is slightly smaller. Longstroke tappet block has a curved side, mystery has straight sides.
The stem diameters are identical, so it fits the guide. But the curve ground on the foot is at 90 degrees to the long face, and presents a smaller width to the cam lobe.
Only one follower is listed from 1949, so possibilities are that it is an earlier version, or from a completely different model. It is unlike any follower from any BSA Post War model.
Struggling a bit to get an answer, any ideas? It is stamped BSA, with Piled Arms logo, Mystery is the on the left, genuine on the right.
Swarfy.
