Okay so i have a 1984 Ford f150 inline 6 bought off craigslist. It had the original feedback carb on it when I bought it. The previous owner had messed with the fuel emissions control crap and the truck started to run crappy after a while. So upon further research, I decided to go ahead and do the popular dura spark II conversion on this truck. I got a 'box', distributor, coil, and carb off an old inline six sitting in a junkyard. It looked like the owner of the truck had done a dura spark conversion as well. So after I completed the conversion and timed it correctly(or so i thought) i started it up and it pops at idle. once you give it gas it gets smooth and runs like it should at high revs. The carb i put on there from the junkyard is a carter 7636s. I searched this carb and found out its originally for a 4-cylinder?! is that my problem? I'm thinking the carb needs to be rebuilt but maybe it's something else. Possibly the electronic choke isn't working? I also read that it could be a valve issue. Havent removed the valve cover to inspect things yet but plan on doing so tomorrow or sometime this weekend.
Any help is greatly appreciated!
thanks.
ps, here's a youtube video i made so you can see the problem.

 

Running quite rough, like it's got a dead hole or 2. Recheck the plug wires, firing order is 153624. If that's correct, pop off the valve cover, and see if there is one (or more) rockers that aren't moving (much, or at all).
Also check for any large unplugged vacuum ports.

 

Firing order is correct. Definitely pulling the valve cover tomorrow.

 

Okay, krwagon01, I'll take a stab... [by the way, welcome to the forum!]

Looking at the carburetor from the passenger side, there is a vacuum port on the lower part of the carburetor [near the EGR] which currently is connected via a rubber hose to the vacuum tree on the intake manifold. That is wrong. That vacuum port should be "ported" vacuum and is where my distributor is connected. Check with a vacuum gauge connected to the port and most likely, there will be little or no vacuum at normal idle speed [~650-750 RPMs]. While checking this, be sure to plug the port on the vacuum tree, which will be open once you disconnect the rubber hose.

The following is just theory on my part, but perhaps the way it currently is connected to the vacuum tree, which is "manifold vacuum", a strong vacuum signal is being introduced to the carburetor at idle, which is messing things up. When you increase RPMs and everything smooths out, that might be because as you open the throttle plate, manifold vacuum drops so there would be less influence. The engine sounds pretty normal at the elevated speeds, so before chasing a bad valve theory, try rerouting the vacuum hoses. [(1)Plug the port where you now have the distributor connected; (2)connect the distributor vacuum to the 1st vacuum port, I discussed; (3)plug the vacuum port on the vacuum tree, which is now connected to the 1st vacuum port, discussed]. Then try to start the engine. Most likely, you will have to adjust the idle speed as well as check the timing and air/fuel mixture again.

The vacuum port presently being used to provide vacuum to your distributor is high on the carburetor [above the throttle] and most likely was used for EGR or other emmissions. Connect the vacuum gauge to that port as well and see how it responds.

If the place where you are now getting vacuum for the distributor is showing vacuum @ idle [should not as designed by Ford], then this will advance the timing substantially @ idle and can cause popping or other misfire conditions.

I hope this will help!

 

Thanks for the replies but I switched the vacuum hoses around the way you described with no changes. The current port that the distributer hose is connected to, draws a very slight vacuum at idle. I opened the valve cover to find a big mess of gunked up oil and dirt. I will report back with any progress after valve inspection and possibly some pictures.
Thanks