My truck is stock, has a two barrel carb on a cast intake and never wants to start after it gets hot and then sits for a couple of minutes or more.I looked at the archives and could not come up with a solution.I rebuilt the carb and that helped a little so then I added pertronics and that helped with overall starts but the problem still remains.I can smell gas fumes very strong after it sets hot for awhile so I took off the air filter to see if gas was boiling out of the float bowl but did not see any or any where else.All new plugs,wires and cap,coil good,rotor new and the engine runs great with 76,000 miles on engine.Also new exhaust manifolds,new three row radiator,hoses,thermostat and it runs in the cool. I will be driving this truck a lot pulling a trailer in 100 degree plus heat and would not like to worry if it will start or not on the road.Is there a throttle body carb that will adapt to this engine or am I stuck with a carb.Any ideas will be appreciated.

"bowties in the rearview mirror"

 

Two things come to mind. One are you sure there isn't gas leaking. Two is the gas boiling but not showing signs of boiling out?

Craig

 

Thanks Craig,I have checked for other gas leaks and found none,how would I know if it boiled out when I see no fuel going into the manifold?Would one of those plastic spacers help?

"bowties in the rearview mirror"

 

I have the same truck but a '72 and am having an identical problem. Starts right up in the morning and then each time after it is harder and harder, strong smell of gas etc. Have you figured out what the cause is. Any advice is deeply appreciated. Pulling my hair out.

 

Khiggi49,I finally got tired of the truck not starting and decided to rebuild the carb again.Here's what I found,the carb spacer had burned out on the backside and I could not see it until I removed the spacer(vaccume leak),the gaskets on the carb top were leaking slightly(gas smell)accelerator pump was leaking gas thru the seal(gas smell),choke pull down had a pinhole in the diaphram (was not working),the base gasket below the carb spacer was made for a smaller bore motocraft carb and was acting as a restrictor plate (less power),the float hold down spring was not holding the float pin down so the float bowl was slightly overfull all the time (hard starts) and last if not least it was real dirty.
After cleaning up all the hard parts I broke open the Walker carb kit,it had everything I needed but the choke pull down diaphram so I called a carb re builder .He told me that the choke pull down does not come in any rebuild kit so I got one from him ($ 15),check yours if your carb has one for any little pinholes as they render it usless.He also told me to straighten out the accelerator pump cover as they warp outwards over the years and start leaking gas as mine was doing.I did not like the flimsy accelerator pump cover and looked at one from a newer carb and saw that it was built way stronger than the older cover so I swapped the cover and rod off the newer motocraft to my 73 carb and no leak.The original carb spacer had no vaccume port at the back and was split at the center where the two throttle bores come together so it had about a half inch opening there.The only carb spacer I could find had a vaccume port at the back and the two throttle bores were not connected as there was no space open between them so I plugged the back port and put her on. Remember if you have to get a different carb body make sure that you get one with the same size throttle bores as yours,my carbs bore was about 1.76" and is what size that was used on most big block applications according to my carb guy.Smaller bores are in the 1 5/8" size,hope this helps.
After the install of the new carb it started right up with none of the old problems.A little idle mixture tune and it runs like never before.After running it in 100 degree heat for 20 minutes I turned it off and let it sit for 10 minutes,it started right up and no gas smell at all.The passing kickdown works perfect and it runs like a new truck.Been a couple of days and still runs perfect. The closed bore spacer seems to have helped but I can not say for sure as there were so many problems to start with.

"bowties in the rearview mirror"

 

Thanks Nod,
I've got the carb off and soaking in cleaner. Guess I'll try one more time to rebuild before I cave in and buy a replacement carb.
Astonishing that you found and diagnosed so many different contributing factors to your problem.
I appreciate your advice.

 

khiggi49,hope your carb is an easy fix,mine still starts up whenever I want it to but I still need to try and tune it so it idles a little smoother.The only other thing I need to do is to shorten the newer style accelerator pump rod as it is about 1/8" too long so when I take off right now the pump does not come on soon enough.That is an easy fix for this weekend. I went to fix the accelerator linkage and decided to check the length of the round steel pin that goes in the accelerator pump housing and sure enough the pin in the kit is about an eighth of an inch shorter than the pin from the donor parts carb.Lucky I kept the old one so I buffed it out and put it in and that took care of my linkage problem.I am always learning something about these old trucks.

Remember to clip the float bowl retainer spring over the needle seat nut as I did not do that on my first rebuild and caused a rich condition all the time.Some carbs have this and some do not,I did not realize what I had done until this rebuild,never to old to learn I guess.Let me know how yours works.

"bowties in the rearview mirror"