Distributor changes
...that seems really high to me, shouldn't it be like 30-32 degrees total ish...
yer confusing the word 'total' but don't feel bad because you're not the only one to use it that way.
Total mechanical timing is initial timing plus maximum mechanical advance.
Total timing while driving is mechanical timing at that rpm, plus vacuum advance.
Mopar Performance wanted to make one distributor work reasonably well for hot stock and mildly hot rodded engines.
So when following
their instructions, set mechanical timing at 2800 rpm. For a magnum, that means 32* at 2800 rpm.
Idle timing will end up being whatever it ends up being. Measure it so you have a reference point. You MUST measure the rpm and write that down too.
(They didn't want to, or care to, explain how to tweak timing at idle. And most customers probably didn't want to go there. If you want to tweak it, we can come back to this.*)
Once mechanical timing is established, then take a drive with a vacuum gage attached so it can be seen from the inside. You or your passenger (or gopro) writes down the manifold vacuum while driving at steady highway speed (like 60 mph).
Then use that vacuum measurement so the total timing while cruising (about 2800 rpm) is 50*.
Say you measure 18 "Hg when cruising. There's already 32* mechanically at 2800 rpm. The vacuum advance needs to add 18* when 18"Hg are applied. That will equal 50*. A vacuum pump with gage is needed.