My ‘49 3600 (216) typically runs well, however, once or twice a year when driving in temperatures above 90° it will unexplainably shudder, and then stall at a red light. It will not restart until it sits with the hood open for about an hour. I do not believe the truck is overheating, I can let it sit and idle in the driveway for 20 minutes on a sunny 92° day, and the gauge never gets above approximately 190. I do notice on the times that it stalls and won’t restart there is fuel leaking from the carburetor at the throttle linkage. Both sides of the carburetor at the throttle linkage linkage are leaking fuel. It happened today, temperature outside was 91° but, again, temperature gage was just slightly above 180°. My Shadetree mechanic brain is out of possible causes. Any ideas? Thanks so much, I love this site and all of your help.
This sounds like a problem we used to have back in the day. The fuel in the fuel line gets so hot it forms bubbles, and that kills the engine. Cooling it off fixed the problem every time. Here's what you can do to verify it. Get a can of ether. When the engine dies again, spray the metal fuel line with ether. If it starts right away, you've located the issue. It's usually caused by a fuel line that is too close to the engine. Find a way to route the line farther away from the engine, and the problem with go away forever.
Take a look at your metal fuel line. If any of it is touching or very close to touching the engine, move it away by bending it slightly. Those engines came with standoffs to hold the fuel line away from the head.
