367 here with Eddies, an AG, and a 750DP.
In run my cooling system at 207*, and run unwrapped TTIs.
No boiling/no percolation; at least not in the short term.
I run a one-piece 3/8 fuel-line from pump to carb, isolated and free-standing off the engine, but still runs in a similar to the factory route. At the back, near the tank, I have installed a large metal-canister EFI filter. The 3/8ths supply line is routed inside the frame rail.
A common trouble spot is the rubber jumper from the tank-sender to the hard line. My solution is to double-clamp it on each tube, staggering the screw-heads 180 degrees. This prevents the pump from sucking air, thru the pinch-lines.
Air trapped in the supply line from pump to carb will present very similar symptoms as fuel boiling in the line. When you shut the engine off, the air will travel uphill to the float valve, and accumulate at the trailhead. As soon as the float valve relaxes, the air will scoot into the bowl. If/when the modern crappy fuel evaporates from the bowl, you will have a long crank-time until the pump refills the line.
An electric fuelpump would cure this; but I hate those things on the street. My HD Carter pump was new in 1999, and seems to still be working fine.
To be fair, Here in Manitoba the daytime highs rarely exceed 99 degrees, and very rarely for more than several days in a row.
To be truthful, in about 2005, I cut a hole in my hood and mounted a nice aftermarket aluminum air filter housing, on top of my hood. Then I sealed my carb in a box to the underside of the hood. I did this NOT because of fuel troubles, cuz I had none. I did it cuz the underhood air temp was often running way over 300* and everybody knows you can't make power sucking hot underhood air. I just thought you should know, before some clown on FABO tells you.
Modern gas is made up from many different compounds. Some of those evaporate at or near 100*, others need over 200*, others even higher. The low-temp ones help for starting. The high-temp ones won't even become flammable until under compression.
When you shut your fully warmed up engine off, Immediately the lighter compounds begin to boil off, then the next, and the next until you have nothing left but the syrupy stuff., and your engine will not start on thatchit. So you gotta crank until the pump delivers some better stuff. But if that better stuff was stored in the gastank for a week, or the car has been in the hot sun all day, guess what, the good stuff is gone. So there you sit, cranking and pumping the pedal, with your fingers crossed.
The only cures I know of are
1) is to seal the fuel system, and collect those lighter compounds, for a later burn or
2) to put something into the fuel, to bind some of those lighter compounds to some heavier ones, to help them hang around a lil longer. or
3) to carry a small bottle of fresh fuel, on board, in my case, under the hood, at all times. After my car has been sitting for several days I just splash some of that bottled-gas into the cold intake, and hold the throttle down a bit, as if I was doing a clear-flood procedure. When the engine fires up, I just keep the Rs up until the Fuel-pump has brought up some fuel from the tank, then it's business as usual.
