Pinging

In the past I have always had trouble timing the engine with a light and end up doing it by a vacume gauge and ear! If I use a light and try for a factory setting about 8/10* before the engine will die. I have a true TDC. When I use a vacume gauge and adjust the dist to get max vac she idles well and the performace seems good but pings bad. I've tried a few things as advancing or retarding the timing but she still pings. I use + gas 89 octine.

Although I've read other posts I'm not up on the "total" timing thing and not sure how to tweak outside from moving the dist back and forth!

Sould I start playing with the screw in the vacume can?? If so which way do I turn it and how much??

This is the stuff I hate:shaking:..Wish you were here!
Thanks