The base timeing on my 1968 289 was set at the suggested 6BTC with the vacuum advance disconnected and plugged. When I revved the engine the centrifugal advance activated at around 2000 RPM: just as it should. Now it is my understanding that when I reconnect the vacuum advance and rev the engine, the timing should advance sooner than before thee centrifugal advance kicks in: if it is working properly.
When I reconnected the vacuum advance line to the distributor, the timing light showed the timing advanced 20 degrees and the RPM climbed by 100 all by itself-I never revved the engine. When i did rev the engine the timing advanced further.
Is is normal for the vacuum advance to have a pronounced effect on timing advance while at idle? I thought it was to be near the base 6 degrees BTC at idle and then advances as the RPMs rise?
What do you all think? I hear no knocking or pinging, it runs smooth, never runs hot...
When I reconnected the vacuum advance line to the distributor, the timing light showed the timing advanced 20 degrees and the RPM climbed by 100 all by itself-I never revved the engine. When i did rev the engine the timing advanced further.
Is is normal for the vacuum advance to have a pronounced effect on timing advance while at idle? I thought it was to be near the base 6 degrees BTC at idle and then advances as the RPMs rise?
What do you all think? I hear no knocking or pinging, it runs smooth, never runs hot...