My stock engine runs a bit rough when cold - smooths out as it warms up.

When I start it, the idle is only 500; so it would seem the choke is not working correctly.

Comments/suggestions/experience welcome....

Thanks

 

Is the choke coil plugged in? Does the line have power on it? Is the choke adjusted properly? Is the fast idle set properly? Is the choke pull off working?

BigBlockk

Later.....

 

In addition to the above questions, are all your vacuum hoses intact and in place? How about the "stove pipe" to the exhaust manifold on the driver side?

 

Sounds like the vacuum break diaphragm is ruptured. This is the small cannister in front of the choke. If the diaphragm (rubber) inside the cannister is ruptured the choke will not unload slightly at idle. When the engine is first started (cold), the choke wants to close completely. The vacuum break diaphragm pulls the choke valve to a preset opening once the engine is started. This opening is usually about 1/8 to 1/4 inch. If the diaphragm is ruptured ....no opening will take place. The engine will run rough and want to stall because it isn't getting the required amount of air needed. Once the engine starts to warm up and the choke starts to open....the idle will stabilize. Easiest way to tell if it is working is to start the car when cold...observe the opening (slightly) of the choke valve. If there is no opening of the choke valve 1/8 to1/4 inch and the choke valve remains completely closed then the rubber diaphragm is ruptured. You can test it by removing the vacuum hose to it .....push the arm into it then cover (with your finger) the vacuum port. The diapragm should hold it in. If it pushes back out while your finger is covering the port then you have found the problem.They are easy to change and not very expensive.