[Supra_Freak_7m]

When you had the engine rebuilt, Which head gasket did you use? Did any material get taken off of the head? Which Fasteners did you use? ( I.e. ARP Bolds, Studs or factory ) Water pump get replaced at rebuild time? Thermostat? What is your ignition timing set at? Did you jump the proper terminals before you set the ignition timing? Cam/Crank timing set perfectly? Are you following the proper engine rebuild/break-in oil change interval?

Check these things and if you have any questions about what i listed here, feel free to ask....