I recently rebuilt my fathers 4160 style 4bbl with vac secondaries on his 75 with a 390. It was very dirty but it cleaned up nice and a factory Holly kit was installed. The plastic thermostat cover was broke so the choke probably had not been working so good. I replaced it , kept the mixture screws where they had been before, (bout 1.25 turns out) , new spacer gaskets under the carb now and its not running good. The plugs and points have been neglected so I have not checked them out yet ( dont know why he let a mechanic convert it years ago) but the only think I can think of on the carb that might be off is :
The small rode coming down from the choke plate has a long bend at the bottom. I put it UNDER the plastic counterbalance on the back of the thermostat because the one at Checker Auto was like that on the wall, It seems to be stuck on high idle forever too, thats why when I get back there, will try putting the rod in after the counter balance falls under it. The truck is 100 miles away till I get back and its been single digits and Teens BRRRRRR! is this the missing link? No screws were adjusted or removed during rebuild, Other than the mixtures that were put where they at. THANKS

 

Make sure that the choke spring actually goes inbetween both of the lever prongs so that it will open the choke and close the choke. This wil also control the fast idle cam action.
Jimmy

 

10-4 good buddy, the new housing came with the spring and its stuck on there GOOD!

 

I mean, the piece that moves in the housing that opens and closes the choke flap. Make sure that the spring goes into that piece properly.
Jimmy

 

The loop on the spring does engage the little choke lever and when you turn it left to right it does open and close the choke plate

 

So you are saying that they choke plate opens up, but the plastic lever doesn't fall to release the fast idle?

 

Ya its like that small plastic counter balance on the back of the thermostat housing is getting in the way or in the wrong position to allow it to come off the high idle cam,

 

Try backing out the fast idle speed adjusting screw a couple of turns. It's on the throttle shaft befind the choke.
Jimmy