Choke Problems

[doodah man]

Lately, I've had two problems when I cold start my truck. The fast-idle cam engages when I floor the pedal, but, once started, the engine idles really low and rough. The choke plate opens about 1/8". If I pry the choke open with a screwdriver another 1/16" the idle picks up and gets smoother. If I let go, it goes back to rough and low. The second problem, is that once the engine is warm and idling high and smooth, the fast idle cam fails to disengage when I tap the pedal. I had to push the cam down by hand to get the idle to settle down.

Once the engine is fully warmed up, it idles and runs like a top.

It's a 1975 Rochester Q-jet on a stock 350.

Seems like I have two problems here. Anyone seen this before? I'm wondering if the choke isn't opening because it's cold outside or if it's sticking. Can I adjust something so the choke plate opens a little more? Does that also have something to do with the fast idle cam not disengaging?

Any help is appreciated.

[VetteVet]

You probably have one or more of the following bad. The choke is adjusted incorrectly, the choke pull offs are bad or missing their vacuum hoses or they are adjusted incorrectly.

Here is a very good breakdown of the carb and it happens to be a 1975.

http://www.vetteprojects.com/kstyer/quadrajet.htm