Is this what they call vapor lock? (1 Viewer)

[85roktoy]

77 40 desmogged factory carb hasn’t been rebuilt. Once It’s hot after running it starts but idles very low like it wants to stall and runs very rough for about 5 minutes then it’s fine. No carb fan that I can see. How do I correct this?

 

[1911]

Vapor lock will usually prevent it from starting at all, in my experience.

I would start by adjusting the valves and checking the timing and the functioning of the dizzy advance mechanism.

 

[Pighead]

Sometimes, when my Pig gets hot, it likes a little choke when starting. Just for a minute or two.
Don't know why but it works.

 

[85roktoy]

OK so if it’s starting then it’s not vapor lock because it is starting. It just runs really rough for the first 10 minutes or so after restarting once it’s already hot.

 

[SteveH]

The term 'hot soak' refers to all of the carburetor parts getting hot after you park (hence one reason Toyota installed the carb fan starting in the mid-1970s). My FJ40 would stall and die in the street 45 seconds after refueling on a hot day - quite a safety hazard.

 

[85roktoy]

The term 'hot soak' refers to all of the carburetor parts getting hot after you park (hence one reason Toyota installed the carb fan starting in the mid-1970s). My FJ40 would stall and die in the street 45 seconds after refueling on a hot day - quite a safety hazard.

How did you fix the issue?

 

[DangerNoodle]

How did you fix the issue?

An insulator on the carb base may help, a plastic or wood spacer. I was fighting fuel temps with my sniper for a little while, added in a poly spacer, and it seemed to help a lot.

 

[SteveH]

How did you fix the issue?

The short answer is AFI TBI. I think part of my long-term problem was a leaky fuel switching valve that would randomly let air into the fuel line. Having said that, at high elevation and with crummy modern gas, I had endless fuel issues in the summer until I converted to EFI. I did leave the carb cooling fan in place, since no fuel systems like heat.

 

[Comet]

Heat soak is a real issue. Check the route of the fuel line from the pump up. I had my 2F 60 series bent right up against the hot engine. Moved it back out and also did the manual over ride on the carb cooling fan so it ran for 30 minutes after turning the truck off. I am not sure which task yielded better results since I did them at the same time.

Do you have any cracks or holes in the heat shield surrounding the carb?

 

[85roktoy]

Heat soak is a real issue. Check the route of the fuel line from the pump up. I had my 2F 60 series bent right up against the hot engine. Moved it back out and also did the manual over ride on the carb cooling fan so it ran for 30 minutes after turning the truck off. I am not sure which task yielded better results since I did them at the same time.

Do you have any cracks or holes in the heat shield surrounding the carb?

I’ll have to look for cracks and holes but I don’t believe so. Mine doesn’t have the carb cooling fan either.

 

[65swb45]

See post #2. I would add only that a vacuum gauge will help demonstrate how @GA Architect theory intersects with your symptoms.

 

[Comet]

The bracket holding the fuel line at the front of the engine is important too. The vibration usually creates a hairline crack near the carb thats tough to pick up on.