HEI ignition secrets

[1969c10joe]

for right now any info on adjustable vac advance is helpful is my battery weak if it has trouble turning over at 13 initial?can vacuum advance increase timing while engine is cranking if its hooked up to manifold vacuum I wouldnt think so but......even one degree more matters over the years ive noticed there is a two degree window sweet spot ill post my timing numbers geezer sorry cant do it today though im gonna have to retest and write it alldown