Like was said before...
Figure out your total timing without pinging. Something like 32-36.
If you want 12 degree initial and 32 total... pick a 20 degree curve. Rev your car past the rpm of the curve you picked and set it at 32. Now double check to see if your initial is at 12 degree at idle (32 deg minus 20 deg equals 12 deg initial). You're done.
