timing Q...

[Billla]

I'll respectfully disagree right back Timing is specified at a set RPM; as you adjust the timing you should continually re-adjust the idle as req'd. It makes no sense to have a high idle with mechanical advance in and trying to set timing.

There's nothing wrong with dropping the distributor to establish initial timing; it's easy to set the engine at whatever you want for static timing and then point the rotor directly at #1. For example, I usually set my engines to 16 degrees BTDC and drop the distributor with the rotor pointing at #1 when starting for the first time - this works fine. If I misunderstood something in your post, my apologies.

Erratic timing can come from many sources and isn't limited to just the advance mechanism IMHO.