Timing issues on '71 318

I set mine at TDC like the sticker said and it sucked.
Bumped it up till it preignited at wide open throttle and then backed it off till the pinging went away.
Chked it with the timing light and distributor disconnected and it was at about 15 BTDC.
Hooked the vacuum back up and chked it again with the light and the timing mark on the dampener could not be found any longer. (was up under the water pump)
The engine sure likes it a lot better.
You can't really go wrong having the timing set as far advanced as you can but where there is no detonation.
Advance it, drop the idle down to compensate, test drive and keep doing that until it starts detonating and then back it off a little.
note where the vac advance line on the distributor is and about a quarter inch retarded from there should do it.

"Old school by ear method"