Ignition breakup would make the afr go massive rich due to unburht fuel entering the pipes, We had an issue years ago with not enough air entering the carb,solved with a hientz air filter system. Heat shields and ducting air to the exhaust system to blow the heat out seems to help. Connected a hose to the back of the radiator to right in frt of the #1 pipe and ducted out under the car. Cool the carb and air entering it as well as you can by sheilding it.