QUICK REFERENCE CHART SIZING FOR GREDDY PERFORMANCE PLUMBING
Dash Nominal Common Approx.. ORB AN / JIC
Size ID (in) Fraction ID (mm) Thread Thread
-03 0.1875" 3/16" 4.8 mm 3/8"-24 UNF* 3/8"-24 UNF
-04 0.2500" 1/4" 6.4 mm 7/16"-20 UNF 7/16"-20 UNF
-05 0.3125" 5/16" 7.9 mm 1/2"-20 UNF* 1/2"-20 UNF
-06 0.3750" 3/8" 9.5 mm 9/16"-18 UNF 9/16"-18 UNF
-08 0.5000" 1/2" 12.7 mm 3/4"-16 UNF 3/4"-16 UNF
-10 0.6250" 5/8" 15.9 mm 7/8"-14 UNF 7/8"-14 UNF
-12 0.7500" 3/4" 19.1 mm 1-1/16"-12 UNF 1-1/16"-12 UNF
-14 0.8750" 7/8" 22.2 mm 1-3/16"-12 UNF 1-3/16"-12 UNF
-16 1.0000" 1" 25.4 mm 1-5/16"-12 UNF 1-5/16"-12 UNF
-20 1.2500" 1-1/4" 31.8 mm 1-5/8" -12 UNF 1-5/8" -12 UNF
The sealing method differs:
AN/JIC: 37° flare seat
ORB: O-ring at the base of the fitting
Quick Automotive Reference
Application Common Size
Brake lines -3 AN
Clutch lines -3 AN
Vacuum (Boost) lines -4 AN
Fuel feed (400-600 hp) -6 AN
Fuel feed (600-1000 hp) -8 AN
High-power fuel feed -10 AN
Oil cooler lines -10 AN
Catch can drains -10 AN
Radiator hoses -16 AN to -20 AN
Dry sump scavenge -12 AN to -16 AN
NPT Thread Size Chart (½" through 1")
NPT Size Thread OD (in) Threads per Inch Approx. Drill Tap Size Typical Use
1/2" NPT 0.840" 14 TPI 23/32" (0.719") Fuel systems, oil ports, sensors, regulators
5/8" NPT 0.940" 14 TPI ~3/4" (0.750") Less common; specialty adapters / industrial fittings
3/4" NPT 1.050" 14 TPI 59/64" (0.922") Fuel pumps, filters, coolant lines
1" NPT 1.315" 11.5 TPI 1-5/32" (1.156") High-flow fuel, coolant bulkheads, race plumbing