Bob, here's what your OEM curve may look like.
This is for the Volvo Penta engines, but it may be similar to Crusader....... check and verify.
Note that most of these Marine Ignition advance curve graphs do not show nor include BASE advance on the vertical scale.
So this one is showing the progressive advance only.
BASE must be added when doing the math.
Example: the dark graph line shows 22* @ 3.2k rpm. If you add a BASE of 8*, your total would be 30*, etc, etc.
Note how the curve tapers off and flattens out at/near 3.2k rpm.
If your advance continues some above this RPM, is not necessarily a deal breaker.
If you have total faith in your digitally advancing timing light, then use the method that Mark points out.
Once set, and if you want to check or verify, put the light in standard strobe mode, and check again.
However, your balancer or flywheel must be marked off for this method.
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