well, i bought this truck about two weeks ago and it is pinging...the timing is at 8degrees BTDC and im running premium fuel....it seems to be getting about 10MPG right now, which could be better, especailly at 2.40/gallon. but i know it's the nature of the beast. im not really concerened with improving mileage as much as im concerned with it running rich/pinging should i switch to a lower octane, or should i advance/retard the timing???? it's a 350 w/ a t400 and it's been rebuilt(not sure on specs) but it does have a mild cam and a holley 750CFM carb. thanks ya'll!!!!!!