Comments on my 340 plug under mag
If you want to compare with a distributor timing, like we did here, the areas outlined in blue are initial and mechanical advance. The area outlined in green is initial, plus mechanical and vacuum advance.
I don't know what sort of compression, heads, pistons and cam are in the engine, 32 at idle would be for extremely poor combustion and low density fill. A factory 340 would want around 12 - 15 degrees at 640 if emissions was not a concern. AFR around 13:1. A leaner mix will want a little more spark lead and probably will have to idle at 700 to 750 minimum.
Compared to factory timing, the WOT advance looks slow. But that's for an iron headed factory 340 and maybe other changes are at play.
Continuing with the distributor equivalent, there should be no vacuum advance below 6.5 "Hg (101 to 79 kPa MAP).
Between 6.5 "Hg and 10.5" Hg may be able to add in more spark lead. If the engine needs enrichment below 10.5"Hg, then it shpouldn't want more spark lead. That's the fundementals discussed in that other thread.
A MP distributor would provide timing something like this.
If you want to compare with a distributor timing, like we did here, the areas outlined in blue are initial and mechanical advance. The area outlined in green is initial, plus mechanical and vacuum advance.
I don't know what sort of compression, heads, pistons and cam are in the engine, 32 at idle would be for extremely poor combustion and low density fill. A factory 340 would want around 12 - 15 degrees at 640 if emissions was not a concern. AFR around 13:1. A leaner mix will want a little more spark lead and probably will have to idle at 700 to 750 minimum.
Compared to factory timing, the WOT advance looks slow. But that's for an iron headed factory 340 and maybe other changes are at play.
Continuing with the distributor equivalent, there should be no vacuum advance below 6.5 "Hg (101 to 79 kPa MAP).
Between 6.5 "Hg and 10.5" Hg may be able to add in more spark lead. If the engine needs enrichment below 10.5"Hg, then it shpouldn't want more spark lead. That's the fundementals discussed in that other thread.
A MP distributor would provide timing something like this.