Okay...doubling the accurate measuring capability of the factory timeing tab without inaccuratly applied balancer tapes by a nearly invisible 30 second modification to the engine balancer.
Here we go....12 degrees of Advance is measured on the factory tab...and 2 degrees of retard. So I rotate the engine around to place the factory balancer notch directly opposite 12degrees on the factory timeing tab (each mark on the tab is 2 degrees of rotation).
The degreeing tool is a simple fine cut triangular file....no measurements, no tapes to put on wrong and then fly off, just a file come engine degreeing tool.
With the factory balancer notch at 12 degrees Advance, carve a smaller notch at 0 degrees (TDC). Outline em both in silver sharpie or white out or what ever ya got handy.
Now I had the motor rough timed at an estimated 15 degrees BTDC....the factory balancer notch above and off the scale of the tab. With my extra notch carved I started the engine, put on the timeing light and the new smaller balancer notch lined up at the first mark above 0 on the timeing tab....so, the 12 degrees on the tab, plus the first mark on the tab equals 14 degrees BTDC. Pretty close considering I eyeballed the setting initially, (The guesstimate of 15 degrees BTDC placed the factory balancer notch off the top of the factory tab as you recall.) This is much more accurate. I can even wiggle in odd numbers like 17 or 23 degrees BTDC by placeing the new smaller balancer notch between the marks on the timeing tab.