Rough idle in gear
 

63 Belair with carbed sbc 350 & TH400 (missing kickdown)

I have rebuilt the edelbrock 1406, plugged power brake port, replaced intake manifold gaskets, new vacuum line from carb to trans modulator and from carb to vacuum advance. Other misc things I did was new plugs and adjusted valves.

Will start right up and idle around 950 and will occasionaly rise to about 1400 and go back down to 950 (In park/neutral)

When in D or R, will idle so low that it stalls in a few seconds.

Any ideas?

Would the missing kickdown have an affect on how it idles in gear? I'm thinking the modulator valve may be the culprit....

what kind of vacuum reading are you getting at idle? is the gauge holding steady, or fluxuating a lot. and what is your base timming set at...

Adjust the idle mixture a little higher, (richer), see if that helps. if it did, you were running too lean at idle, and you need to find out why (vac leaks somewhere). Of course, it could just be that idle mixture adjustment was off a little :D

What I do for idle mixture screws is turn them all the way in then 2 and a half turns out.

Assuming it's a vintage distributor, you probably changed your points. Did you change your condenser? An old one will allow your spark dwell to go too long, giving you a sloppy, yellow spark, instead of a crisp blue one.

Reset your ignition specs after you replace that condenser, it may surprise you.