What cam?
What is your cyilinder psi?
steel or aluminum heads?
what is your advance curve on the dist.?
I run 200-205 psi 16 initial 34 total(start at 1000 rpm-all in at 3000 rpm) 48 total with manifold vacuum starting at 8 inches of vacuum on a 10.3-1 383 with aluminum heads in hot(100
+) weather with no probs.