Here in sunny So. Cal. I can only get 91 octane for my 86 300E, often blended with God know what these days. On hot days especially, I notice a fair amount of pinging, particularly when accelerating from a stop in 2nd gear going uphill. Sound like a can full of rocks under the hood. Is there a resistor value I can switch to that will allow me to retard the timing slightly overall? I'll put up with the loss of a little power or fuel mileage to prevent holing a piston.

Gary

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