These are all questions about my 1975 2WD, 390 (2bbl Motorcraft carb), C6 auto... I did a quick search on vacuum, but nothing seemed to apply to this old of a truck...

Anyone know where I can find a vacuum diagram for the 390 and carb? I'm mostly concerned with where to plug in the vacuum advance. I'm disabling most of the emissions stuff. It's all pretty nasty anyway...

Next, are the heater doors the only thing inside the truck that's run off vacuum? I can't think of anything else that might be. Well, my heater controls are all FUBAR, and someone has wired in a toggle switch for the blower motor on high. Until I can figure out what's all been done I would like to just plug the vacuum port for the inside accesories, since I can only assume this would lead to a vacuum leak inside, and the heater doors are not working anyway (it seems to be stuck on defrost, and A/C compressor is missing)

Next, my truck was missing the kickdown rod. Does this rod control anything other than kickdown? Also is there just one vacuum line to the tranny? There are two hard lines, but one appears to be just hanging, not attached to anything on either end. and does that one line (or two if need be) get attached to manifold vacuum?

and finally the choke. There seems to be a small vacuum? fitting on the bottom of the choke housing. What is that for, where does it go? Is it needed, can it be plugged? and does the choke get 12volts? I can't find a choke wire under there, so I just plan on running a new one from the fuse box. Or there is some type of valve with several plugged hoses running from it, and two wires running to it. This appears to be some sort of emissions device. If it has 12volts I might use it for the choke...

any thoughts/suggestions?

thanks...

 

Well, I think I got it all figure out this evening. Put on the new carburetor, with new plugs, wires, cap, rotor, fuel filter, PCV, breather, fix a few things, and it's like a new truck...

My buddy even brought over an extra kick down rod. Didn't have a chance to see if it would fit, though. It came off a 302/C4...

 

your heater doors are controled with rods and leavers that conect to the slidding *****...on the heater contols, thier is no vacum..thier is a small spring with a loop that concects to the leaver.

 

Hmmm... So, the vacuum that runs into the cab... does it only control the heater valve? Also, do you know if the heater valve is normally open or normally closed. In other words if the truck were off, no vacuum whatsoever, would the valve be open or closed?

 

I had a 77 Ford f-150...when I turned on the heater controls thier was a puff sound, I guss. that would be vacum, so I'm wrong...I did experiance problems with the rods/leavers behind the heater contols, over time they just wore out.