Why are my distributor cap terminals burnt?

Righty Tighty

Are you familiar on how to adjust the mechanical advance on that distributor ?

You don’t use the limiter plate with this distributor

Like Mattix stated , you loosen those two Allen screws and open or close those two tabs on the plate for mechanical advance on how many degrees you want

Factory blue springs , timing all in by 2400 RPMs

I run 16 initial with 18 mechanical for a total of 34 Degrees with ported vacuum at cruise