Completely rebuilding the carb isn't a whole lot more time consuming than replacing the jets. Just for grins......how old is the gas? If it is old enough, it will cause the engine to spit and die. Ask me how I know.

 

Ok, I'll bite, how do you know?

Actually, the gas is several months old since the weather here has been raining for a couple months so the car hasn't been driven much. As well, the tank is getting near empty, water in the tank from condensation?

 

hmmm, gas will "gel" up given enough time and make things kinda clogged up. Could be your problem. Try some STP fuel line cleaner or a similar product. also fill her up with good fuel.

Here in So. Dak. the gas of choice to improve the oxegen content is gasoline with 10% ethanol. If that is available try a tank full of that as the alcohol makes a nice sticky gas solvent. I would not run more than the one tank of it though as it may also not be condusive to the rubber pieces in your fuel system. [8D] The alcohol will also help absorb any water in your fuel tank.

a good carb cleaner would be a cheap start.

 

It looks like I may have found the problem.

It does appear there is a vacuum leak. The throttle shaft does move around somewhat and when held in a certain position on each side of the carb, will allow the car to idle properly, even when put into drive. So, most likely, the soft brass bushings in which the throttle shaft is held are worn out and air is getting in there.

Solution 1: rebuild the carb and replace the throttle shaft bushings.

Solution 2: get a new Holley carb and sell the Fomoco for rebuild.

 

Sounds like you found the solution. Congrats! The reason I know about bad gas and its' effect on an engine, is that I stored my 65 for 10 months out of the year, and after so many years of this, the gas went south. It acted just like your description, so that is why I suggested maybe you needed to change the fuel. But, that wasn't the problem afterall. I would rebuild the Motorcraft carb. I am not a big fan of Holley carbs, but that's just me.

 

I wouldn't mind just rebuilding the carb but I'm worried that rebuilding the bushings is beyond my scope.

After reading the vendor bashing thread on Mustangs Unlimited, I ran across the ponycarburetors.com site and it appears I have an Autolite 4100 - heres what they have to say of this carb:

Has anyone dealt with these guys? I wouldn't mind simply replacing mine with a rebuilt and selling them my core if what they say about this carb is true.

 

Which are the replacement carbs from Holley and Edelbrock for the Autolite 4100?

 

There are not really any replacement carb.... if it is the right flange for them, they should bolt up and run. If i was you, i'd send yours to pony carbs, and let them rebuild it, or buy a rebuilt one, from them. Glen(soaring) swears by them. Is that what you have on yours Glen????

 

Go to Pep-Boys and buy a new Holley 570cfm. They are the easiest to work on and adjust. You can adjust the floats without tearing the top of the carb off. They are just as easy to rebuild. Sorry boys, just my opinion.[8D]

 

Go get yourself an Edelbrock 500.....