ive just rebuilt my enging and it has less than 50 miles on is so far. i am having problems tuning it i guess because it wont idle the lowest it will run without stailing is 1100. the carb is old and sat free from gas for a goos 6 months while the car was being rebuilt. could it be that the carb needs to be rebuilt? could it be the timing or could it be the idle mixture?

let me know if you have any ideas thanks, J

 

Check for vacuum leaks around the carb and base of the intake. Also timing plays a huge part in idle, as does the carb settings.

The screws on the front of the carb only adjust the fuel flow into the idle circuits, try starting with them 1.5 turns out.

Next make sure you dont have gas pouring into the manifold from the carb. The float and or needle and seat might be stuck or just not working, allowing fuel to overflow the carb vents. The float level could be too high, that would burn your eyes at idle and cause a rich condition that stalls the engine out. Conversely it could be too low causing a lean condition and plain running out of gas.

Float level has a HUGE impact on carb performance and driveability. On some carbs you can even crutch incorrect jets (to a point) or make minor adjustments in flow through the float level. High float level will allow fuel to flow into the boosters and main circuits sooner creating a slightly rich condition at just above idle. Too low and it can cause a stumble because the pump shot isnt enough to hold the engine over untill the fuel can flow through the boosters and circuits.

Finding where a certain engine likes the float to be set is trial and error, its not a one size fits all just below the sight plug. Thats a good place to start, but you can tailor it a bit more with some time. The jets should be pretty close from before, just make sure the carb is running good before you delve into the world of jets.

When you set the timing be sure the vacuum advance isnt connected to the carb and the port on the carb is plugged to avoid the vacuum leak.

Here is a trick I use on a carb that has been sitting a while or develops an idle issue during driving. Remove the air filter assembly, rev the engine up to around 3000-3500 rpm. Place your hand over the primary throttle bores briefly then remove it. The engine should pull on your hand a bit and the rpm should drop. Dont let it die off because it will be way rich at this point. Also be aware that you can get a nasty cut from the engine vacuum so be careful. Do that a few times and see if the idle improves. It pulls the crud that builds up over time in a carb out of the circuits and vents, thus making it run better.

I found the neighbors dont like it much when I do that since my cars are quite loud..

 

Thumpin has it all covered. The carb needs attention. Either rebuild it, or replace it with a new rebuilt one if you don't know how to do all the tricks he told you how to do. I would first start with spraying some carb cleaner in the carb you have, and see if that cleans it out. But the bottom line, is that your carb is needing attention.