My 1969 f250 has a 390 engine with a 2-barrel carb. If I put a 4-barrel carb. on, will it help with the problem of vapor locking? What are some of the best ways of solving this problem?
Thanks

 

It depends on what you are calling Vapor lock. Usually what folks call vapor lock is any
disruption of fuel being delivered to the carburetor.

There is no actual mechanical way that fuel vapors can stop liquid fuel being pumped to the carburetor if the tank has fuel, the draw tube & sock are good, there are no cracks or holes in the fuel lines, the filter is clear and the pump works right.

If you have a hot start problem, it may be caused by the carb boiling fuel into the intake when the hot engine is shut down causing the engine not to fire up & run, until the carb refills . . . . .
But if you go from a 2V carb to a 4V carb you would be increasing potential problems because there is 2X the quan of fuel present to heat & spill into the intake. Are you running the correct heat shield insulator base palte under your 2V carb Now?

FBp

 

I never put a different base plate on, but that doesn't mean that the person who owned it before me put a different one on that isn't the correct one.
I was wondering if I could put a little electric fuel pump somewhere in-line before the fuel pump that I have now. Then I would mount a switch in the cab for it and every time it vapor locks, I could flip the switch and it would pump new fuel into the carburetor. Would something like that work?
I really want to solve this problem when it doesn't start when the engine is hot.
Thanks

 

I would try a phenolic spacer. That's usually the cure for hot start.

 

I always thought vapor lock was fuel boiling in the fuel line, and thus the pump didn't have any liquid to work with. I've seen people try to insulate the fuel line. Whatever the cause, I use to cure it years ago with an electric pump back closer to the tank, away from the hot engine.

 

Another posibility if it starts cold but not when hot is the coil is bad. Try a new coil. Have had that before.

 

There is some kind of a metal spacer underneath of the carburetor right now. It looks like it serves no purpose but to raise the carburetor up higher. Is that the phenolic spacer or does the phenolic spacer goes on top of that piece?

 

That metal spacer does nothing to dissapate heat. Phenolic sheet is a hard, dense material made by applying heat and pressure to layers of paper or glass cloth impregnated with synthetic resin. A phenolic keeps the heat away from the carb.
What I believe you're experiencing is fuel boiling in the float bowl.

 

While vapor lock is rare, it does occur. But if you just have a "hot start" problem, perhaps this will help:

http://www.thecarburetorshop.com/Tro...m#Hardstarthot

Jon.