Have 1978 AQ120B volvo penta. Almost finished with engine. Cooked my coil. Found there was no ballast resistor wired to the coil. A straight 12 volts. Have a stock coil 20,000 volt. What ohm resistor do i need. I have 1.6 across the coil post. Maybe 1.3 resistor. Does any one no a formula for this.
