Pete, the ignition timing is not the cause of it running for a few seconds then stopping (that is fairly certain to be a fuel problem), but because you are aiming to get to the bottom of how the engine works, I suggest you go through the process of checking it. The whole way around the flywheel is 360 degrees - any circle consists of 360 degrees, that is the definition of a degree of angle. You want to find how far on the outside of your flywheel coincides with the 6 degrees before TDC that is the correct ignition timing. 6 degrees, out of 360 degrees, is one part in 60, or one sixtieth of the circumference of your flywheel. One sixtieth of 502.6 mm (pi isn't exactly 3.14) is 8.4 mm, so your timing mark should be 8.4 mm clockwise from your TDC mark. When the flywheel reaches that 8.4 mm before TDC position, the points should open and the ignition should be triggered. Once you make the timing mark, it is fairly easy to check the ignition timing either by zapping your fingers as described above, or by using an ordinary xenon or neon ignition timing light.
If you have good fuel flow from your fuel pipe, the next possible cause of your problem is that the float chamber needle is sticking: it will close fully, but it won't open more than a few thousandths of an inch.
