So I was driving the copper truck to Mexico last night (77 F350 460 C6 2wd), and while sitting in line, it got a bit warm-about 230. I was running the heater to provide a bit more cooling, but it stalled right out on me. Tried to restart it, and it would crank and crank, but never kick.

So I pushed it out of line (there's a good time) and into a parking lot. Popped the hood and everything looked fine. Poured some gasoline down the carb, but it still wouldn't kick, although it would turn over fine.

I let it sit for a half hour, and after it got down under 200, it fired right up. I drove around the block and parked at the Circle K. Everything seemed fine, so I braved the line again. This time, it started getting warm, but never over about 220. Again, it wanted to stall at idle, but I kept the RPM's up, and it kept running. Temp stayed consistent 210-220, but I had to keep the RPM's higher and higher. Without the brakes, I would have been doing at least 40!! Got a little scary when the brakes started to fade, and the truck was still wanting to stall. Then it started backfiring. I guess that was due to the raw fuel in the exhaust.

Anyway, I made my destination, and it seemed to be ok after it cooled down. I made a couple of short trips, then waited til after 3 am to come home. No line at the border. Drove home fine.

Oil is fine. Coolant is fine, radiator is new, as is the water pump, backing plate, heater core, hoses and thermostat.

So, what do the experts think???

 

I'm not an expert but here's my nickel.

When ya first pulled up to the line, the cooling system was still dealing with the built-up heat generated by the engine and could not deal sitting still with no air flow except at idle and likely, just a mechanical fan. In essence, the cooling system got "spiked" with a big heat load.

A potential strategy to deal with it is to allow the engine system to cool by driving around at slower speed and RPM before idling in a standing line. But even that may not resolve the issue given your description the second time in line.

Other possible solutions:
- Electric fan(s) plus the commensurate upgraded alternator.
- A pusher electric fan (manually switched) to supplement the mechanical fan in these situations
- Fan shroud but I'm sure ya already got one.
- Redline Water Wetter or Royal Purple Ice to reduce surface tension

- Electric fuel pump, bypass regulator, and return line.
- Insulated fuel lines and a carbon fiber heat shield for the carburetor. Buy some sheet stock like Carbon Fiber Sheets and shape it soemthing like picture below. Unlike a metal heat shield, carbon fiber is of a low thermal mass, which means it loses heat quickly:

 

Thanks, that does give me something to look at!

The fan is the original 77 design (no clutch) and runs directly off the water pump. The blades do seem kind of small to me. It has the factory shroud, although it is broken at the top right corner.

I never got the impression that the engine (coolant) was overheating, so I'm leaning toward the fuel overheating. I'll look at a way to insulate/re-route the fuel line.

Where do y'all suggest placing an electric fuel pump? I've heard good arguments for the back and the front of the vehicle.

 

Electric fuel pump should be mounted as close to the fuel tank as possible. They do a better job at pushing fuel rather than drawing/siphoning fuel.

As for the model - something off the shelf at any parts store that doesn't require special tools to remove and replace. I recommend some sort of gate valve between the tank and pump so the tank need not be emptied to replace the pre-filter, post-filter, or even the pump itself.

 

In addition to what HIO said, idling for extended periods with a c6 in gear drags the motor speed down and produces extra heat in the motor and transmission. If everything is in good shape your truck should prevent and overheat but if your carb is idling rich or lean, your coolant isn't mixed 50/50 and it is hot out that might be enough to spike the temperature.
I like to kick it into neutral if it looks like it will be a long wait. If the temp creeps up you can crack the throttle some to cool it down without working the tranny and creating more heat there..