Super Six, Slant Six Timing

AJ/FormS said

Now there are two more things to do. #1, is power timing, and #2 is the Vcan.
But first take it for a spin. You will be testing for spark-knock/detonation/pinging/rattling, whatever term you are familiar with. You will be testing for it, in 2nd gear, and from idle to 2000 rpm, with various throttle settings.Anytime you hear detonation,grab an rpm reading and back off the throttle. Write it down and include an approximate throttle setting, like WOT, 3/4, 1/2, or 1/4 throttle.Work your way up slowly. Take your time. Take a week or more.If you never hear it, move up to 3000 and repeat. And if you still never hear it, move up to 3500, and repeat, and once more to 4000. Stop there.At 3000 you only need to test 3/4 and Full throttle. At 4000,you only need to concern yourself with full throttle. But if you ever hear the dreaded rattle, back off the throttle immediately.

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The hard part is telling the difference between mild spark knock or pinging, and detonation. Pinging is OK and many engines in the 70's suffered from it but kept going fine as the manufacturers leaned carbs to meet emissions; it is light sounding and high pitched, similar to a marble rattling in a tea cup. I had a '76 Dart Lite that pinged all the time with moderate to large throttle openings if I had it in too high a gear and at low RPM's; in 4th gear OD up a mountain at 50 mph, it was guaranteed to ping... a lot. I sold the car with over a quarter of a million miles on the engine, going strong.

Detonation is a much heavier sound, like a big hammer striking aluminum, and sometimes the engine can seem like it is jerking around.

BTW, an HEI ignition (yes, redundant!) will act like some level of advance, as it gives a much better start to the spark and the burn process in the cylinders.