Make sure the top engine cover shroud is on proper. Those Quantums have a small pan lip on the carb side the shroud needs to fit in proper. It will make a random metallic sound if the shroud is not on right.
Clean the cooling fins and block while you are there.
Regap the ignition coil to 0.006". Measure a piece of paper to set the gap. These coils are NOT flame throwers far as spark goes using an open gap style tester. Don't use a bulb type to test spark. You need to stress the coil out making sure she is healthy.