What ever you do don't keep detonating it. That is VERY harmful to the engine. Figure out what's going on. Get your timing straight, that's very important. You have a heavy vehicle so that engine will see a lot of stress.
If the timing doesn't cure it try running some racing gas and see if that cures it, if so, you may need to lower your compression ratio.
Do you know what the compression is? Does it have aluminum heads? What rear gears? Stall? etc... All these things can effect your pinging.