85 d50 won't run right at all

Hi guys, I have a problem with my sons truck. It's a 85 d50 custom with a 2.0 motor. We had the motor rebuilt, put it back in the truck did all standard stuff you need to do to a fresh motor. We got it running but it will only run with the choke and won't excelerate very good. It's running like its really lean but the plugs are really black as if it's running rich. We've only had it running for about 20 minutes total. The carb and exhaust are stock; plugs are the RN9YC's. I've checked all the vacuum lines and for vacuum leaks, plug wires etc; but can't find anything wrong. Any help will be greatly appreciated. Thank you

I'd start by rechecking the timing belt alignment.

Hi Scooter26,

Here's so easy things to check:

Make sure the two fuel lines on the carb are not reversed. The one that feeds the accelerator pump has less pressure than the one that goes to the floats and the jets. The line closest to the valve cover feeds the floats.

Is the engine timing set correctly. It should be about 5 degrees BTC at 700 rpm. The exact specification for your truck should be under the hood.

Did you gap the plugs?

Do a compression test. It should be 149 psi +/- 10%.

John