After rebuild, it ran great for 1 day, then started to surge and sounds really bad at idle. Like a diesel truck, and smells really bad. No smoke, just bad fumes. Previous (before rebuild)idle mixture screw settings were 4 1/2 turns out. After rebuild should be back to 2 1/2 or stay with 4 1/2 turns out? It revs fine, just surges when try to hold steady around 2000rpm and won't idle or idles real rough.
I installed the new power valve that came with the rebuild kit. They call it an economizer valve. It does look slightly different than the one that came out of it. It's a little shorter. Think I should try putting the original one back in?
If the mixture screws are set properly I think the power valve might be blown. A simple cough/backfire through the carb is all it takes. If the original PV wasn't blown, reinstall it to see if that's the prob.
I think it would be worth putting the old power valve back in. If that helps, get one from Ford. Also, check the fuel wells that lead to the boosters. If they get some crud in there, they can really burp fuel into the motor and make it act like that.
The Motorcraft carb is a pretty good part. They almost never give trouble.
Ok, let's see...I've put the original power valve back in and the original needle and seat back in. It ran good for a minute, but then started this silly desieling at idle again. What a pain! I'm beggining to think that it must be something other than the carb, since it did run good for a day or so before it started acting up. I'm going to try supplying gas from another source (a can) and see how that works.