You are correct. However, I should have been more clear: I was talking about part-throttle pinging. It was a problem I had with my '66 that was caused by an overly aggressive (i.e., worn out) vacuum advance. I could stop the pinging by accelerating harder. (Which drops vacuum and dials back the advance.) Finding the right advance was tough. Year One had it. I have had no trouble since installing it. Chris H. 60 NY T&C 66 Crown Convertible 66 LeBaron --- dardal@xxxxxxxxxxxxxxx wrote: > > > Note on vacuum advances from the mid-60's: The > most > > common ones available are set up for the emission > > controlled needs from 1965 on - called C.A.P. > They > > provide nearly double the advance (up to 17.5 > degrees) > > and if installed will cause your early 60's engine > to > > ping like crazy. Be sure you are betting the > right > > one. > > > > Chris, you may be more familiar than I with the > early 60 big blocks, but the > vacuum advance advances only at part load. Engines > typically ping at full load > where there is zero vacuum, so the vacuum advance > setting has no effect. I > think it may be unlikely that an engine without > deposits will ping at part > throttle if proper octane gas is used. More advance > at part load could help > gas mileage and reduce coolant temperature a bit by > reducing exhaust > temperature. > D^2 > >