What is the 1/8" NPT Drill and Tap Kit used for?Updated 6 days ago

To tap a hole for 1/8"-27 NPT threads, GlowShift recommends using an R-size drill bit. An R-size drill bit measures approximately 0.339" in diameter and does not have a standard fractional equivalent. The closest commonly available drill size is 21/64", although GlowShift recommends using the specified R-size drill bit for the proper thread fit.

GlowShift’s 1/8"-27 NPT Drill and Tap Kit provides the tools needed to drill and tap a hole directly into an exhaust or intake manifold for installing gauge sensors and fittings. This includes creating a threaded port for an EGT thermocouple probe or Boost Gauge fitting.

The kit includes:

R-Size Drill Bit: Cobalt-finished, high-speed steel, 118° point, 4-3/4" overall length

1/8"-27 NPT Tap: High-carbon steel pipe tap, 2-1/4" overall length

Using the proper drill size before tapping is important to ensure the 1/8"-27 NPT threads are formed correctly and the gauge fitting or sensor installs securely.