318 Poly Vibration

The position of the timing tab has absolutely nothing to do with which direction to turn the distributor. Some tabs are on the right, some on the left, but ALL 318s, Poly OR LA turn the distributor counter clock wise to advance and clock wise to retard. You need to get that timing RIGHT before you diagnose further. "I" would start with "around" 15 degrees initial and see "how it likes it".