i have a f150 with a 351w just put in about 2000 miles ago. now that it started getting cold out it is idling rough (it chugs). put new plugs, wires, cap, intake gasket, rebuilt the carb, timed it. im stumped anything would be helpful.

 

Is your choke set properly? If it's not opening enough, it could be causing it to run rich and load up.

 

yes when the truck get up to running temp the choke opens all the way up

 

Do you have the original aircleaner on it with the hot air system hooked to the exhaust manifold?

 

no i do not

 

it has the orignial air cleaner but no hot air off the manifolds

 

If it starts up fine with a fast idle, and then sits there a minute or two and starts slowing more and more and spitting out more and more black smoke and running rough, I suspect the carb is icing up, especially if it seems to do it worse on cold damp rainy days.

The aircleaner should have a temp sensor mounted in it with vacuum lines. One line goes to manifold vacuum, and this is the one you have to take loose each time you pull the aircleaner completely out. Another line comes out of the sensor and goes to the snorkel to the damper door actuator.

The bottom of the snorkel should have a short pipe coming out of it where the flexible aluminum piping clamps. You can buy these pipes in the store. It ran down and hooked to a sheetmetal heat stove that was mounted around the exhaust manifold.

The sheetmetal heat stove is usually taken off and thrown away, or rusted and has fallen off. If you have headers or your heat stove is gone, most of the time you can rig something up to work. I have made my own heat stoves out of aluminum flashing for my header installs.

You would be surprised and how uncomplicated the heat area has to be to get just a little heat into the carb. You could even take the full length of aluminum piping you get, clamp it onto the aircleaner, and then take scissors and split the other end about 6 or 8 inches and slip it around the exhaust pipe and use a piece of wire to hold it on. Anything to get a little bit of heat into the carb.

 

ok i will have to try that. because when i go down the road it runs fine. dosnt miss a beat. its just when its idling. and i live in northeast ohio and its like 0 degrees out

 

also does anyone have any pictures of their air cleaner set up

 

This picture is probably not exact, but it has all the main components that the system uses.

AutoZone.com Repair Guide Image

 

I modified a Ford OEM exhaust manifold shroud (EDIT: I think from a 70's truck) to fit
around my headers; I don't remember exactly what was involved but it wasn't real difficult, I
think I just had to use some tin snips and some spacers:



My air cleaner is from a late-70s sedan and the vacuum routing is exactly as explained by
Franklin2 - manifold vacuum to temperature sensor, temperature sensor to valve in the
snorkel.