Actually I’m not assuming either. What I’m assuming is the heat is the problem: heat can cause fuel boil causing vapor lock, and heat can cause expansion in the coil and/or distributor disrupting spark. So, I’m shielding lines first and looking at the radiator efficiency specifically to isolate the electrical. My premise, hypothesis, is heat is the cause and the other two are symptoms of that cause. Yes, I’m treating one of the symptoms first but I after reading the bulletin and understanding how easy it is for fuel to evaporate, I think shielding the lines is prudent anyway. That’s why I chose that as a starting point.