I'm a jeweler using a Smith "Little Torch." Recently, when the gas is lit, the flow isn't constant; the length of the flame (amount of gas) changes (increases) around every 2 seconds (which is really, really annoying). Anyone know what this means?

What gasses are you using: MAPP, Propane, Aceteline?

Are you using oxygen?

Does the flame do it's 2 second thing just using fuel or not?

I'm using Propane and Oxygen.

Yes it happens with just fuel.

It's also kind of cold here: 20 to 30 degrees F. Would that affect anything?

I suspect it's dirt if it happens when the head is absolutely still.

It might be useful to know if orientation of the torch makes any difference from horizontal to verticle and at 45 deg angles.

Take the torch outside.
What I would do is disconnect the lower gas line from the tip and just burst a little gas out. Take the tip off the torch hea and put the body back on. Open the gas valve on the tip all the way. Burst gas out using the regulator. Then put the tip back on and do the same thing.

Another possibility is a hole in the hose. This you might be able to find by lighting the torch and holding it steady and flexing the hose along it's length while observing the flame.