Pressol » Screw-in taps and screw-in holes with sealant (sealing in the thread)
Drill & Tap Kit - 1/8" NPT Thread
Amazon.com: GlowShift 1/8-27 NPT Drill & Tap Kit - 1/8" Carbon Steel Tap & R High Speed Steel Drill Bit for EGT Probe Installation to Exhaust Manifold : Automotive