My ‘68 383 with non ethanol 91 octane purrs at idle and 600 rpm with the factory setting of 7-1/2 degrees. My mechanical advance and vacuum advance are tuned to factory settings as well. If I advance it further I need to lower the idle and then it seems like I get a mid range roughness. If it is running and idling at 10 degrees and your vacuum and mechanical advance have something close to the factory curve you should be good. I don’t think your altitude is much different than mine here in Fargo.
I will say I am not that familiar with the 413.
I will say I am not that familiar with the 413.
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