Carb Jets

[ford38v8]

Originally Posted by TomC750

Forgot something - When the car is surging, which is not dramatic, if I pull the choke out a bit to richen it a bit, it stops surging!

OK, I got it... your fuel pump is not delivering. The problem can be the pump itself, an air leak before the pump, a restricted fuel line before the pump, or a non-vented fuel tank. Surging is the key word in your problem. I take you at your word that your carb has been correctly rebuilt and float adjusted properly. Your choke pulled out slightly helps pull the fuel through the pump.

You should have from 1 to 4 lbs pump pressure.
An air leak or a restriction will reduce volume and pressure. Do you have a glass bowl pump? An air leak may show bubbles there. Use cork gaskets there, soaked in oil. Check connections and hose clamps. Wire spring hose clamps are no good, replace with worm gear clamps. Fuel lines can deteriorate and develop pinhole air leaks. A fuel line leak before the pump will never leak gas, but will suck air.

A restriction can be dirt in the fuel lines, a fuel filter needs replacing, or an internally collapsed flex line. These are reproduced fuel resistant, advertised in the V8 Times under Shewman. Do not get the check valve type.

Non vented tank requires a vented cap. Have you replaced fuel caps lately without regard to venting?