No bueno
The motor’s ‘pinging’ noticeably under load (accelerating from a stop/lugging it in a higher gear). Runs without issues under any other circumstances/rpm./road speed.
It’s never done this before. Nothing was done over the winter that might have precipitated this, premium fuel made no difference.
Checked timing thinking it might be too advanced. Seemed ok, though moving the backing plate over a broad range affected the timing very little. You’ll recall I made a clear cover for the RH motor end-cap and set the timing dynamically (engine running) with a timing light. Advancer function seemed fine as well, but did not verify its function at various rpm’s other than for full advance.

I’m thinking the 42-year-old springs on the advancer unit may have lost tension and timing is advancing too soon. As well, the idle speed is sometimes slow to drop down when the throttle is closed (another advancer fault indicator?). Still waiting on arrival of NOS advancer unit.
Finally, noticed worn area on the advancer unit tip. Very slight contact on the 1-6 pick-up. Pickup is secure, and there is very little play on the advancer shaft.

Any thoughts on the issue while I await the new advancer, anything I might have missed, anyone else have a similar experience?
Mike C.