Reply to "Need some diagnostic expertise please: Engine/ignition?"

I went through everything again today. Vacuum is good. 18 at idle, climbs to 25 when rev'd and no fluctuations. A manual pump hooked up to the distributor verified that the advance does respond well to vacuum. Testing the vacuum at various locations showed no leaks in the system.

Checked the timing again and it was set at 10. Did it move after I set it last time? Who knows, but when re-set to 6 it ran fine right up to 5000. Hmmm.

Spark seems good and indeed, the engine does respond when the advance is changed. I just expected it to be more affected by such large changes in timing at idle.

I bled the cooling system again (got a bit more air out) and now she runs great and pretty much stays under an indicated 200 on the water temp gauge. Still a bit warmer than the 190 she used to run before, but maybe a tired thermostat or some crud is impeding flow. I'll look into that next.

Maybe it was just bad timing and air. Seemed fine after an hour long run over the back roads here. Up to a hundred and tons of loping around at 25—30. I am happy again.

Thanks for the input George and Ron.