Timing Retarding @ high RPM

I develop ignitions and efi. Here is how timing timing is acurately measured without timing lights. Use a logic analyzer. A logic analyzer captures multiple logic signals, on conjunction with a high speed reference clock.

An example: capture dual sync signals (2), CDI logic trigger, and attenuated clipped coil primary. From those you can figure out actual ignition timings and delays. I can help with simple math,. On a V8 cylinder signals are 90 degrees apart. If half the distance 45 degrees, easy.

For bench work use micro programed for making signals like dual sync distributor, with ability to ramp RPM from cranking to past red line. Feed signals into ECU, use 5v supply pull ups to digital outs, feed those to logic analyzer, capture as above.