Nucoil Technical Information
Comprehensive thread specifications including Metric, UNC/BSW, UNF, UNEF/UNS, BSF, BSC/Brass, BA, 8 TPI UN, BSP, NPT, Sparkplug, Carburettor, Caterpillar, Cummins, and Harley Specials with tapping drill sizes and tapped hole outside diameters
Metric
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (mm) | |
| 2.0 x 0.4 | 2.10 | #45 | - |
| 2.2 x 0.45 | 2.30 | #42 | 2.79 |
| 2.5 x 0.45 | 2.60 | #37 | 3.09 |
| 3 x 0.5 | 3.20 | 1/8" | 3.65 |
| 3 x 0.6 | 3.20 | 1/8" | 3.78 |
| 3.5 x 0.6 | 3.70 | #27 | 4.28 |
| 4 x 0.7 | 4.20 | #19 | 4.91 |
| 4.5 x 0.75 | 4.80 | #12 | 5.47 |
| 5 x 0.75 | 5.20 | #5 | 5.97 |
| 5 x 0.8 | 5.20 | #5 | 6.04 |
| 5 x 0.9 | 5.20 | #5 | 6.04 |
| 6 x 0.75 | 6.20 | #D | 6.97 |
| 6 x 1 | 6.30 | 1/4" | 7.30 |
| 7 x 1 | 7.30 | 9/32" | 8.30 |
| 7 x 1.25 | 7.30 | 9/32" | 8.62 |
| 8 x 1 | 8.30 | 21/64" | 9.30 |
| 8 x 1.25 | 8.30 | 21/64" | 9.62 |
| 9 x 1 | 9.30 | 23/64" | 10.30 |
| 9 x 1.25 | 9.30 | 23/64" | 10.62 |
| 10 x 1 | 10.30 | 13/32" | 11.30 |
| 10 x 1.25 | 10.30 | 13/32" | 11.62 |
| 10 x 1.5 | 10.50 | 13/32" | 11.95 |
| 11 x 1 | 11.30 | 7/16" | 12.30 |
| 11 x 1.25 | 11.30 | 7/16" | 12.62 |
| 12 x 1 | 12.30 | 31/64" | 13.30 |
| 12 x 1.25 | 12.50 | 31/64" | 13.60 |
| 12 x 1.5 | 12.50 | 31/64" | 13.90 |
| 12 x 1.75 | 12.50 | 31/64" | 14.30 |
| 13 x 1.25 | 13.30 | 33/64" | 14.60 |
| 13 x 1.5 | 13.50 | 17/32" | 14.90 |
| 13 x 1.75 | 13.50 | 17/32" | 15.30 |
| 14 x 1.25 | 14.30 | 9/16" | 15.60 |
| 14 x 1.5 | 14.50 | 9/16" | 15.90 |
| 14 x 1.75 | 14.50 | 37/64" | 16.30 |
| 14 x 2 | 14.50 | 37/64" | 16.60 |
| 15 x 1.5 | 15.25 | 39/64" | 16.90 |
| 15 x 2 | 15.50 | 39/64" | 17.60 |
| 16 x 1.5 | 16.50 | 21/32" | 17.90 |
| 16 x 2 | 16.50 | 21/32" | 18.60 |
| 17 x 1.5 | 17.50 | 11/16" | 18.90 |
| 18 x 1.5 | 18.50 | 23/32" | 19.90 |
| 18 x 2 | 18.50 | 47/64" | 20.60 |
| 18 x 2.5 | 18.80 | 47/64" | 21.20 |
| 19 x 1.5 | 19.50 | 49/64" | 20.90 |
| 20 x 1.5 | 20.50 | 13/16" | 21.90 |
| 20 x 2 | 20.50 | 13/16" | 22.60 |
| 20 x 2.5 | 20.80 | 13/16" | 23.20 |
| 22 x 1.5 | 22.50 | 57/64" | 23.90 |
| 22 x 2 | 22.50 | 57/64" | 24.60 |
| 22 x 2.5 | 22.80 | 57/64" | 25.20 |
| 24 x 1.5 | 24.50 | 31/32" | 25.90 |
| 24 x 2 | 24.50 | 31/32" | 26.60 |
| 24 x 3 | 25.00 | 31/32" | 27.90 |
| 26 x 1.5 | 26.50 | 1 3/64" | 27.90 |
| 27 x 1.5 | 27.50 | 1 5/64" | 28.90 |
| 27 x 2 | 27.50 | 1 5/64" | 29.60 |
| 27 x 3 | 28.00 | 1 3/32" | 30.90 |
| 30 x 1.5 | 30.50 | 1 13/16" | 31.90 |
| 30 x 2 | 30.50 | 1 13/64" | 32.60 |
| 30 x 3 | 31.00 | 1 7/32" | 33.90 |
| 30 x 3.5 | 31.00 | 1 7/32" | 34.50 |
| 33 x 2 | 33.50 | 1 5/16" | 35.60 |
| 33 x 3.5 | 34.00 | 1 11/32" | 37.50 |
| 36 x 1.5 | 36.50 | 1 7/16" | 37.90 |
| 36 x 2 | 36.50 | 1 7/16" | 38.60 |
| 36 x 3 | 37.00 | 1 29/64" | 39.90 |
| 36 x 4 | 37.00 | 1 29/64" | 41.20 |
| 39 x 2 | 39.50 | 1 9/16" | 41.60 |
| 39 x 3 | 40.00 | 1 9/16" | 42.90 |
| 39 x 4 | 40.00 | 1 37/64" | 44.20 |
UNC / BSW
| Size | Approx Fractional Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|---|
| Metric | Inch | (Inches) | ||
| #2-56 | - | 2.30 | 3/32" | 0.109 |
| #3-48 | - | 2.70 | #36 | 0.126 |
| #4-40 | - | 3.00 | #31 | 0.145 |
| #5-40 | 1/8" | 3.40 | #29 | 0.158 |
| #6-32 | - | 3.80 | #25 | 0.179 |
| #8-32 | - | 4.40 | 11/64" | 0.205 |
| #10-24 | 3/16" | 5.10 | 13/64" | 0.244 |
| #12-24 | 7/32" | 5.80 | 15/64" | 0.270 |
| 1/4-20 | - | 6.70 | 17/64" | 0.315 |
| 5/16-18 | - | 8.30 | 21/64" | 0.385 |
| 3/8-16 | - | 10.00 | 25/64" | 0.456 |
| 7/16-14 | - | 11.50 | 29/64" | 0.530 |
| 1/2-12 (BSW) | - | 13.30 | 33/64" | 0.600 |
| 1/2-13 (UNC) | - | 13.30 | 33/64" | 0.600 |
| 9/16-12 | - | 15.00 | 19/32" | 0.670 |
| 5/8-11 | - | 16.50 | 21/32" | 0.740 |
| 11/16-11 | - | 18.00 | 23/32" | 0.810 |
| 3/4-10 | - | 19.80 | 25/32" | 0.880 |
| 7/8-9 | - | 23.00 | 29/32" | 1.020 |
| 1-8 | - | 26.00 | 1 3/32" | 1.160 |
| 1 1/8-7 | - | 29.50 | 1 5/32" | 1.310 |
| 1 1/4-7 | - | 33.00 | 1 9/32" | 1.440 |
| 1 3/8-6 | - | 36.00 | 1 27/64" | 1.590 |
| 1 1/2-6 | - | 39.00 | 1 35/64" | 1.720 |
UNF
| Size | Approx Fractional Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|---|
| Metric | Inch | (Inches) | ||
| #3-56 | - | 2.65 | #37 | 0.122 |
| #4-48 | - | 3.00 | #31 | 0.139 |
| #6-40 | - | 3.75 | #26 | 0.171 |
| #8-36 | - | 4.40 | #17 | 0.200 |
| #10-32 | 3/16" | 5.10 | #4 | 0.231 |
| 1/4-28 | - | 6.60 | 17/64" | 0.296 |
| 5/16-24 | - | 8.20 | 21/64" | 0.367 |
| 3/8-24 | - | 9.80 | 25/64" | 0.429 |
| 7/16-20 | - | 11.50 | 29/64" | 0.503 |
| 1/2-20 | - | 13.00 | 33/64" | 0.570 |
| 9/16-18 | - | 14.50 | 37/64" | 0.630 |
| 5/8-18 | - | 16.30 | 41/64" | 0.700 |
| 3/4-16 | - | 19.50 | 49/64" | 0.830 |
| 7/8-14 | - | 22.50 | 57/64" | 0.970 |
| 1-12 | - | 26.00 | 1 1/64" | 1.110 |
| 1 1/8-12 | - | 29.50 | 1 5/32" | 1.210 |
| 1 1/4-12 | - | 32.50 | 1 9/32" | 1.360 |
| 1 3/8-12 | - | 36.00 | 1 13/32" | 1.480 |
| 1 1/2-12 | - | 39.00 | 1 17/32" | 1.610 |
UNEF / UNS
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (Inches) | |
| 1/4 - 32 | 6.60 | 17/64" | 0.291 |
| 1" - 14 | 26.00 | 1 1/64" | 1.090 |
BSF
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (Inches) | |
| 3/16"-32 | 5.00 | 13/64" | 0.225 |
| 1/4"-26 | 6.60 | 17/64" | 0.296 |
| 5/16"-22 | 8.30 | 21/64" | 0.366 |
| 3/8"-20 | 9.80 | 25/64" | 0.434 |
| 7/16"-18 | 11.50 | 29/64" | 0.503 |
| 1/2"-16 | 13.10 | 33/64" | 0.570 |
| 9/16"-16 | 14.80 | 37/64" | 0.640 |
| 5/8"-14 | 16.30 | 41/64" | 0.710 |
| 3/4"-12 | 19.50 | 49/64" | 0.850 |
| 7/8"-11 | 22.80 | 57/64" | 0.980 |
| 1"-10 | 26.50 | 1 1/32" | 1.120 |
| 1 1/4"-9 | 32.50 | 1 9/32" | 1.380 |
BSC / Brass
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (Inches) | |
| 1/4"-26 | 6.60 | 17/64" | - |
| 5/16"-26 | 8.20 | 21/64" | - |
| 3/8"-26 | 9.80 | 25/64" | - |
| 7/16"-26 | 11.30 | 29/64" | - |
| 1/2"-26 | 13.00 | 33/64" | - |
BA
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (Inches) | |
| 0BA | 6.20 | C | 0.281 |
| 1BA | 5.50 | #3 | 0.249 |
| 2BA | 4.90 | #10 | 0.221 |
| 4BA | 3.80 | #25 | 0.171 |
| 6BA | 2.90 | #33 | 0.134 |
8 TPI UN
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (Inches) | |
| 1 1/8" - 8 | 29.50 | 1 5/32" | 1.290 |
| 1 1/4" - 8 | 32.50 | 1 9/32" | 1.410 |
| 1 3/8" - 8 | 36.00 | 1 13/32" | 1.540 |
| 1 1/2" - 8 | 39.00 | 1 17/32" | 1.660 |
| 1 5/8" - 8 | 42.00 | 1 21/32" | 1.790 |
| 1 3/4" - 8 | 45.50 | 1 25/32" | 1.910 |
| 1 7/8" - 8 | 48.50 | 1 29/32" | 2.040 |
| 2" - 8 | 51.50 | 2 1/32" | 2.160 |
BSP
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (Inches) | |
| 1/8"-28 | 10.00 | 25/64" | 0.430 |
| 1/4"-19 | 13.50 | 17/32" | 0.580 |
| 3/8"-19 | 17.30 | 43/64" | 0.720 |
| 1/2"-14 | 21.50 | 27/32" | 0.910 |
| 5/8"-14 | 23.50 | 59/64" | 0.990 |
| 3/4"-14 | 27.00 | 1 1/16" | 1.130 |
| 1"-11 | 33.80 | 1 21/64" | 1.420 |
NPT - Taper Pipe Thread Kits
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (Inches) | |
| 1/8"-27 | - | - | - |
| 1/4"-18 | - | - | - |
| 3/8"-18 | - | - | - |
| 1/2"-14 | - | - | - |
| 5/8"-14 | - | - | - |
| 3/4"-14 | - | - | - |
| 1"-11 1/2 | - | - | - |
Sparkplug Sizes
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | (mm) | |
| 10 x 1.0 | Pilot Nose Tap (No drilling required) | 11.20 | |
| 12 x 1.25 | Pilot Nose Tap (No drilling required) | 13.60 | |
| 14 x 1.25 | Pilot Nose Tap (No drilling required) | 15.60 | |
| 18 x 1.5 | Pilot Nose Tap (No drilling required) | 20.10 | |
Carburettor Specials
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | ||
| 3/8" - 32 | 9.80 | 3/8" or W | - |
| 7/8" - 29 | 22.50 | 57/64" | - |
| 1" - 20 | 25.80 | 1 1/64" | - |
Caterpillar Precombustion Chamber
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | ||
| 7/8" - 12 | Pilot Nose Tap (No drilling required) | - | |
| 1" - 12 | - | ||
Cummins Head Bolt
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | ||
| 11/16" - 16 | 18.00 | 45/64" | - |
Cummins Sump
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | ||
| 1" - 18 | Pilot Nose Tap (No drilling required) | - | |
Harley Specials
| Size | Tapping Drill Size | Tapped Hole Outside Diameter | |
|---|---|---|---|
| Metric | Inch | ||
| 1/4" - 24 | 6.60 | 17/64" | - |
| 7/16" - 16 | 11.50 | 29/64" | - |
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