Correct me if I'm wrong here guys but you need to tune the other timing events first. (initial, total without vacuum, mechanical advance rate or curve to a total of about 35° at around 3000 rpm. ) Then you can hook up the vac hose and adjust the can to around 50° at 3000 rpm. Test drive it and if it pings while cruising, back off the vac can. If it pings on acceleration your mechanical is coming in too quick or the total is too much. It can also be caused by too much initial. I thought I had a thread saved about this but I can't find it now. May be someone will chime in.
