I really appreciate all the advice in this newsgroup - you pointed me
to some great sites, now I have photographic guides on how to do
everything from the plug wire re-route to replacing the timing chain
(not looking forward to that).
Where things stand now:
I checked all the plugs and they are all intact - no metal spatters,
no missing electrodes or insulators. They were pretty wet and oily,
but this was after a dose of injector cleaner, and a string of failed
start attempts, so there would be a lot of fuel in the cylinders.
There's a lot of carbon, and some are lighter than others. But I'm no
plug interpretation expert. Photos here, for your opinions:
Engine still won't start. It will turn over vigorously, and fire every
few turns, but it won't start running. I wonder if the latest episode
of detonation actually caused the timing chain to jump, because this
is exactly how a 318 motor I had in the 80's behaved after it had
jumped a notch on the chain. My first thought was I'd put the plug
wires back on wrong, but I checked that against a diagram I found
online and it appears correct.
Thanks again for all the advice!