MrRiden,
That's a pretty clever way of finding TDC, never knew that about the Triumph. For us (BMW), the only way to find TDC is visually through the window. The absolute way to find TDC in an internal combustion engine (with crank & pistons) is to determine the maximum throw of the crank and connecting piston movement towards the cylinder head. That is easily done with the use of a piston stop and a degree wheel. My purpose of finding absolute TDC is only to have an accurate starting point or baseline to try and solve the issue of view angle or parallax in order to reference this position. Basically, the way we look at the different reference marks on the flywheel in both static (valve adjustment) and dynamic (ignition timing) situations. The best solution is the installation of a pointer at very close proximity to the flywheel or in a plane or straight line in-between the case notch to flywheel mark. But how to accomplish this without drilling and installing unwanted hardware or epoxy that may fail is the challenge. I have a few ideas using target marks and various reference marks but have not had the time to spend in the shop. Maybe a futile and ridiculous effort on my part but something I'm playing with in my spare time. I'm aware 2° or 3° may be good enough and not have any ill effects on the equipment. Keep in mind with a flywheel circumference of ±536.6mmm; 1° = ±1.5mm of arc or distance along the outer edge of the flywheel. The window diameter is ±16mm and adding the distance of the window to the flywheel this error increases.
