Thank you.
Per the chart, centrifugal advance is all in at 3600rpm.
The compression ratio on the Commando is nominally 10.5:1. I have TRW domed pistons which were supposed to maintain the stock CR, as opposed to the Egge replacement pistons which (I've heard) result in a lower CR. The compression was in spec last time I checked.
At 22.52MPH/1000RPM in top gear, at 60MPH it is only turning about 2600RPM. 3600RPM would be 81MPH. Absurdly, the horsepower peak at 5200RPM would not be reached until 117MPH (!)... which is why I have always felt this was a bit of a silly spec for a street engine. With a bigger rear end and a 4 speed, it would make more sense.
Anyway, in my example scenario, I'm climbing a grade at around 2600RPM, pulling 11 inches of vacuum. This should theoretically equal about 27º of initial + centrifugal advance, plus 16 to 18 degrees of vacuum advance — so around 45º total. Whatever, it seems to be too much, because it's pinging.
First, I suppose I need to confirm the centrifugal advance numbers by driveway testing — it is possible the mechanical advance springs are worn out (240K miles). If that checks out, then I suppose I want to cut back on the vacuum advance.
I don't want to just dial back the initial advance — it really seems to need it at idle and for initial response. Overall drivability is very good.