[kitcarbp]

rtstrack, without more details or pics, I have to assume your surge tank is highest point in the system. I will also assume its not a full flow surge tank (like original Cobras ) but a partial flow type. The partial flow type surge tank should have a large 5/8" or 3/4" Fill line that exits the bottom of the surge tank and connects to the low pressure side of the rad or lower hose (suction side of pump). The surge tank should have your rad cap on top if its the highest point of your system or above the level of radiator.

The overflow line on the rad cap neck on surge tank, is connected to the catch can or expansion reservoir. Now a good de-gas system will also include a 3/8 line from the very top of the low pressure side of rad (outlet tank) to the top of surge tank at one end of the surge tank, this allows air/coolant mix to rise up to the surge tank from top of rad to contain or trap the air in surge tank until its purged via the vent line to the expansion / catch can during hot/cold cycles. Pics of your set-up would sure help here.