I got a 73 F100 390 2 bbl carb, I had just put a different choke assembly on it cause someone had modified the other, there is a vacuum connection on the back side of it and was wondering were it connects to? or can i just plug the hole

 

Thats probably the suction air to cool the thermostatic coil. As I recall it's a 2" line that runs to the carb.

Or if not stock it could be a pull off vacuum line.

 

On my 351w intake, it had vacuum line that went into the intake manifold, coiled, then came back out. I'm assuming that was so the choke would depend on the coolant temperature in the intake. I blocked it off since I use an electric choke.

 

If it runs on cool air to keep the choke in place how about the high idle selinoid? I had to use different parts to get it to work, but i had to back off the celiniod cause it woudnt slack off , does the choke sencor run that to? my dad mentioned that it heats up to open the choke, now I'm realy lost lol

 

[quote=caplette;6146497]I got a 73 F100 390 2 bbl carb, I had just put a different choke assembly on it cause someone had modified the other, there is a vacuum connection on the back side of it and was wondering were it connects to? or can i just plug the hole[/quote

There should be vacuum to pull hot air from the choke stove (connected by the tubing fitting on the choke housing). This is what opens the choke as the engine warms up. The vacuum is ported through the choke casting into the thermostatic spring housing, down through the tube to the choke stove. On the FE motors the choke stove is in the exhaust manifold on the passenger side. It is identified by two holes in a flat spot on top of the manifold, right above where the exhaust pipe connects and next to #4 spark plug. The other side of the choke stove is connected by a tube to the carb on the back side of the upper casting (you should find a tube under the air horn, sticking down at about 45 deg for a vacuum hose connection). This is so filtered air from the air cleaner housing is pulled in through the choke. If I recall there are no fittings on the choke stove, the tubes are swaged so they just push into the holes. Hope this made sense.
PS If you look up 390 ford engine on Wikipedia they have a picture of the engine in a passenger car that shows the lines going over the valve cover. The plug wires kind of hide the choke stove, but I think you can see what I mean.
Gary

 

thanks a bunch Gary that does help, there is 2 holes there kind of like a push in style hose, but the dam thing is so rusty i dont dare try and pull it out so all i did was, fitted a hose over it back up to the choke,the only thing that was threaded was the housing into the choke were that fitting would go.the old housing someone had cut it off and made it manual took all the things that go with it,so i took part from 3 different carbs (all mastercraft carbs) to get this one to fit and hopfully work. What is the likly hood that a dealer would have that kind of hose? its not a big deal but i dont care for fixing someone elses mess lol Do you know were i could find a diagram for the vacuum hoses and were they go? cause that was a nite mare too to try and figure out,my manuals dont show much of that at all. Thanks again

 

I'm not sure about the dealer having the tubing, but you never know. I think you might be able to check out a few wrecking yards and find what you need. The set up is pretty much the same on all the FE engines in cars and trucks from 1958 to 1976. I think the fitting on the choke is just a 1/4" tubing fitting so if you can find a piece of tubing that will fit in the manifold you can probably just do that. I've seen them hooked up with copper. Try some places like LMC and Blue Oval, they might have it. What accessories do you have that use vacuum? If it is just the power brakes and the distributor it is pretty straight forward. I have the factory service manual for 1975, it should be pretty much the same. I'll see what I can find in it tomorrow when I go to the shop.

Gary