I didn't know this subject was so contentious
It's a free country, so everyone is entitled to pursue absolute TDC in any manner they would like. The only reason I posted was that Neil was looking for an answer regarding the timing on his truck. I assumed that was because he felt there was some problem regarding the timing which as it turns out is the case. The pinging or pre-detonation can be a symptom of improper timing ( too advanced). In a situation like this it is perfectly sound to adjust the timing ( retard) slightly to eliminate it regardless of what the timing indicator reads. Unfortunately today fuel octane ratings are suspect and even if one uses a high octane fuel from the pump you can still run into problems with pre-detonation, especially under a load.