"Pinging" is PRE ignition....
This can be caused by something "hot" (think embers from a fire) firing the charge off before it should be --- and or incorrect timing.
12* initial looks about right but 32* total is probably a bit low on the fully advanced side. BBC's can handle 36* even with iron heads.
So = have you checked the timing with the advance connected? It sounds to me like you might have screwed the vac cannister all the way in - and maybe added timing and just don't know it. Only way to tell is to hook up the old timing light and check it.
What is your vacuum under LOAD? You'll have to get yourself a vacuum hose long enough to run from the source (carb) into the passenger compartment and have someone read it while someone else drives. Cruise light load - flat terrain.... read it - then get it into ping mode and see what it reads. Just searching for an anomaly here...
How are your plugs? If they've been glazed or fouled - they could be the uncontrolled ignition point.
|