Gets hot and stalls out
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.
I'm not sure what bulletin you've read but if it's not very recent (relatively I suppose) it's going to send you down a deep, dark rabbit hole.
Today's fuels do NOT evaporate quickly. What evaporates is the ethanol.
You can test this quite easily. Poor some fuel on a surface and then see how long it takes for it to evaporate. Bring a sandwich. and a good book. It's going to be a while.
It's a real beeotch tuning these engines today with pump gas. Tons of horrible advice out there for sure. It's a two edged sword.
One edge is is that the ethanol flashes off right quick but the gasoline...not so much. As long as you are running an intake manifold with heat (I made that assumption that you were early on, but I'm wrong a lot) you should be fine doing what you can to drop the temperature and not have issues.
Pump gas is graded. We have three grades here. Some people tell me they have four grades but I can't verify that.
Let's call them low grade, Mid grade and premium.
Low grade pump fuel is just that. LOW GRADE. It has the most fillers and junk in it and the best I can describe it is low grade pump fuel is like the wild wild west. Almost anything goes.
Mid grade has a fuel more rules about how much of the fuel can be filler, how much can be detergents and such. This grade is better but it's still pretty open for those other aspects of the fuel.
Premium is just that. It's the best you can get out of a pump. It is far more regulated than the other two grades. It has the least amount of fillers and it uses a much more closely regulated detergent package.
Most of the time I say to run premium in anything with a carb, with the exception of /6 stuff and farm equipment and such. A /6 will usually slurp down anything that will light off and not care.
For everything else, the little that is saved buying a lower grade than premium isn't really doing any favors.
The lower grades usually get less fuel mileage. That's because it takes more fuel to make the same power so you have to fatten it up a bit.
Just remember this. You need the fuel to atomize and then vaporize. It takes more heat to vaporize pump fuel. If you start getting below 180 degrees of coolant temperature you'll need to keep the heat in the intake. I'm talking about keeping the crossover open.
If you want to run cooler than 180 AND if you switch to an intake that doesn't have a crossover (like the air gap, Strip Dominator, Victor or my favorite a tunnel ram) you will need to address the atomization at the carb. The best fix is using a nice annular booster. On top of that, I burr finish every intake manifold and cylinder head I port. That helps too.
I hope this isn't too far down a rabbit hole but pump gas isn't today what it was in the 1960's and 1970's.
