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6.2L LS3 V8 · Thread Repair

LS3 Threads & Thread Repair

Thread size for every repairable hole in the block and cylinder heads, with the matching J 42385 insert and the maximum drill and tap depths for installing it. Tap depth also bounds how far a bolt threads in, which is a useful cross-check on bolt length.

3 tap-depth values in the scanned published table carry OCR typos in the inch column. Each is flagged below and corrected against the metric value; see the corrections page for the full reasoning.

Engine Block (Front/Rear Views)

Kit: J 42385
Hole Thread Insert Max drill depth Max tap depth
1 M8 x 1.25 J 42385-210 22.5 mm / 0.885 in 17.5 mm / 0.688 in
2 M10 x 1.5 J 42385-215 27.5 mm / 1.08 in 22 mm / 0.866 in
3 M10 x 1.5 J 42385-215 Through Through
4 M8 x 1.25 J 42385-210 Through Through
5 M10 x 1.5 J 42385-215 25 mm / 0.984 in 19.5 mm / 0.767 in
6 M10 x 1.5 J 42385-215 32.5 mm / 1.279 in 25 mm / 0.984 in
7 M10 x 1.5 J 42385-215 Through Through
  • Bolt hole 6 is drilled and tapped for aluminum block applications only.

Engine Block (Left/Right Side Views)

Kit: J 42385
Hole Thread Insert Max drill depth Max tap depth
1 M8 x 1.25 J 42385-210 22.5 mm / 0.885 in 17.5 mm / 0.688 in
2 M6 x 1.0 J 42385-205 22.5 mm / 0.885 in 15 mm / 0.591 in Corrected GM: 0.688 in tap depth
3 M8 x 1.25 J 42385-210 28.5 mm / 1.122 in 23 mm / 0.905 in
4 M8 x 1.25 J 42385-210 21.5 mm / 0.846 in 16 mm / 0.629 in
5 M10 x 1.25 J 42385-215 29 mm / 1.141 in 23 mm / 0.905 in
6 M10 x 1.5 J 42385-215 27 mm / 1.062 in 21.5 mm / 0.846 in
7 M16 x 1.5 Not repairable — —
8 M11 x 2.0 J 42385-108 69 mm / 2.72 in 60 mm / 2.36 in
  • Bolt hole 8 has a 30 mm (1.18 in) counterbore included in the 69.0 mm (2.72 in) drill depth. Use sleeve J 42385-315 with the drill and tap.

Engine Block (Top/Bottom Views)

Kit: J 42385
Hole Thread Insert Max drill depth Max tap depth
1 M8 x 1.25 J 42385-210 22.5 mm / 0.885 in 17.5 mm / 0.688 in
2 M10 x 1.5 J 42385-215 42.5 mm / 1.67 in 37 mm / 1.45 in
3 M10 x 2.0 J 42385-104 31 mm / 1.22 in 25.5 mm / 1 in
4 M10 x 2.0 J 42385-104 53.5 mm / 2.1 in 44 mm / 1.73 in
5 M8 x 1.25 J 42385-210 26.5 mm / 1.043 in 19 mm / 0.748 in
  • Bolt hole 2 has an 11.5 mm (0.452 in) counterbore included in the 42.5 mm (1.67 in) drill depth. Use sleeve J 42385-311 with the drill and tap. Bolt hole 3 has a 1.5 mm (0.059 in) counterbore included in the 31.0 mm (1.22 in) drill depth. Use sleeve J 42385-316 with the drill and tap. Bolt hole 4 has a 20.5 mm (0.807 in) counterbore included in the 53.5 mm (2.10 in) drill depth.

Cylinder Head (Top/End Views)

Kit: J 42385
Hole Thread Insert Max drill depth Max tap depth
1 M8 x 1.25 J 42385-210 26.5 mm / 1.04 in 19 mm / 0.748 in Corrected GM: 0.784 in tap depth
2 M6 x 1.0 J 42385-205 20.05 mm / 0.789 in 16.05 mm / 0.632 in
3 M10 x 1.5 J 42385-215 28 mm / 1.1 in 20 mm / 0.787 in
4 M6 x 1.0 J 42385-205 22.5 mm / 0.885 in 15 mm / 0.591 in Corrected GM: 0.688 in tap depth

Cylinder Head (Intake/Exhaust Side Views)

Kit: J 42385
Hole Thread Insert Max drill depth Max tap depth
1 M6 x 1.0 J 42385-205 Through Through
2 M10 x 1.5 J 42385-215 28 mm / 1.1 in 20 mm / 0.787 in
3 M8 x 1.25 J 42385-210 21 mm / 0.826 in 16 mm / 0.629 in
4 M14 x 1.25 Not repairable — —
5 M12 x 1.5 Not repairable — —

Sources

  • GM Service Information: Thread Repair Specifications (6.2L LS3 / 7.0L), Document ID 2055312Captured 2026-06-04

Values are cited as facts. We do not reproduce the manufacturer's prose, table layout, or diagrams.