I installed a new aftermarket manual heater shut off valve on my 56 Victoria 292 and was surprised to see a leak when I warmed up the car to operating temp. Seemed to be leaking where the brass nut screws into the housing. Does anyone know if there is a packing inside the valve?  The valve assembly is cast metal with a brass nut that was 5/8 with a stem that has a metal handle on top. I did tighten the brass nut a bit and the leakage stopped but the shut off handle is now too tight to looosen or tighten to either open the valve more or shut off the flow. I did tighten the brass nut until it bottomed out. Also, does anyone know if teflon tape will stand up to manifold heat on the pipe threads ?  Thanks   George