Leaky adjustable proportioning valve

I have a similar one (chrome) on my 65 Dart, but the logo differs. I have another with a Jegs logo, but both appear from the same factory as yours. The supplied fittings looked like 1/8" NPT threads. Mine had red thread compound on the threads. I agree that it shouldn't be bottomed out on the shoulder. Did you have to torque it real hard to do that? I agree w/ taking it off and adding ~4 wraps of thick teflon tape, i.e. the yellow stuff for natural gas (Home Depot). Don't over-tighten, and if you ever remove it you will have to suck out little pieces of frayed teflon.