what causes pinging in dodge 440?

have the timing set---it's to far advanced---1.warm engine, 2. plug advance vacuum hose to distributor, 3. set timing IAW book---at lowest rpm- ,4. put vacuum hose back on---test run-
if still pinging-remove the cap-and rotor,--check the centrifical advance springs inside the distributor--they might be broken or the advance might be rusty--- re check timing.
rich

rich
March 2009