Ignition timing question: how much total advance

So I've got a 25D dizzy and I've got a pretty persistent pinging issue under load. I've retarded the timing alot and no relief. This is done with the vacuum advance disconnected. So I decided to measure the amount of total mechanical advance I'm getting and it's around 42 degrees. I've got an adjustable timing light so I zeroed it out at idle and set the mark at the big pointer. Then I revved it up to about 2500 rpms and measured the amount of advance. 42 degrees seems way too much. Anyone know how much I should have? The green book doesn't give me any info.


I did take the dizzy apart and cleaned everything so I figured it should be in good working order.

Hi, there is initial,vacuum,and centrifugal. these settings are dependent on how the engine is configured. but the ideal total advance for a gasoline burning engine is 34-36 deg total max advance of all 3.