i have a 79 F-250 with a 460 engine with an automatic transmission. The Carburator is a holly 4 barrel. i was wondering are there any adjustment that could be made to the metering jets? If so, where would they be? The truck runs fine, just a little hard to start after it has run for a while.

 

The main jets are not adjustable. They can be changed, but not adjusted. Sounds more like a heat soak problem. Gas is boiling in the bowls causing it to run down into the intake. I would suggest a heat shield under the carb.
You can try lowering the floats a little bit. There should be a site plug on the side of each bowl. remove one at a time. The fuel level should be just below the site. If gas runs out, then with it idling, on top of the bowl should be a nut with a screw in the middle, just back the screw off enough that you can turn the nut with a 5/8 wrench and turn it clockwise until the fuel level drops just below the site hole. Then, do the same with the rear bowl. This may help.

 

many thanks.. i will give it a try as soon as the weather breaks