I finally had some time today to fiddle with the truck and tried a few things.
First off, responding to some of the previous comments:
Compression - There's 85-90lbs in all cylinders
Ignition - Good old points inside the cap. 6V coil looks fairly new. Plugs, points, and wires recently replaced.
Fuel - Good old mechanical pump. Inline filter
Choke - The choke plate is opening fully when off
As I said originally, the truck generally runs great out on the road, so I'm really thinking this is a carb issue. One of the things I tried was to put my hand partially over the air horn. The engine speed goes up and it idled smoother if I blocked the airflow just right. To my thinking, this implied I wasn't getting enough fuel, and the air/fuel ratio was too lean. I adjusted the idle adjustment screw further out, well past the 1-3/4 +1/2 turns and the truck seems to run better. I was able to drive it without it dying when I came to a stop, but it still doesn't seem "dialed in". The service manual says "If it is necessary to turn adjusting screw more than 1/2 turn in either direction to get a satisfactory idle, internal trouble is indicated." One thing I noticed. I don't see any sign of a gasket between the carb body and air horn. If it's there, it's paper thin.
Any further thoughts from the experts out there?
