Don't be afraid to retard timing.....I ended up with 8* total....with a ten spread direct port , 4.5 psi flowing and a ten spread plate 5.0 psi flowing...both on at the same time. always retard before you advance .

I banged out rings, head gaskets and Pistons when trying the same tuneup with 12* timing. Just because I thought...how could it run with so little timing ? burn and Learn.....lol