Phil - I don't have the best picture but if you look at this picture of mine you can see a bit of red there behind the vacuum secondary linkage. That is the fast idle cam and the screw is down at the very bottom of it and sits on the steps on the fast idle cam except when the choke comes completely off. The bad news is I don't know of any way to really get to the screw to adjust the fast idle without removing the carb or at least raising it up a couple inches to get a small screwdriver on it. The head of the screw is at the bottom with the screw facing up. I need to lower mine a little too and because of the difficulty in getting to it I haven't done it yet.
