Thread Repair Specifications

Table 1: Engine Block– Front/Rear Views Table 2: Engine Block– Left/Right Side Views Table 3: Engine Block– Top/Bottom Views Table 4: Cylinder Head– Top/End Views Table 5: Cylinder Head– Intake/Exhaust Side Views Engine Block– Front/Rear Views

Thread Repair Specifications — figure 1

Engine Block– Front/Rear Views

	Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
	1	M8 x 1.25	210	206	207	208	209	23.0 (0.907)	23.0 (0.907)
	2	M10 x 1.5	420	211	212	213	214	34.0 (1.35)	34.0 (1.35)
	3	M8 x 1.25	61	206	207	208	209	29.0 (1.14)	29.0 (1.14)

Engine Block– Left/Right Side Views

Thread Repair Specifications — figure 2

Engine Block– Left/Right Side Views

Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
Standard Bolts J-42385-
1	M8 x 1.25	210	206	207	208	209	23.0 (0.907)	23.0 (0.907)
2	M10 x 1.25	420	211	212	213	214	34.0 (1.35)	34.0 (1.35)
3	M8 x 1.25	61	206	207	208	209	29.0 (1.14)	29.0 (1.14)
Head Bolts EN-42385-
4	M12 x 1.75	58	51	N/A	52	53	58.0 (2.28)	58.0 (2.28)
5	M12 x 1.75	58	51	57 (Stop Collar)	52	53	58.0 (2.28)	58.0 (2.28)
Cylinder head bolt hole (7) has a unique shallow depth. Use stop collar EN-42385-57. Stop tap and driver at first line. Refer to Thread Repair for head bolt thread repair hardware and procedure.

Engine Block– Top/Bottom Views

Thread Repair Specifications — figure 3

Engine Block– Top/Bottom Views

	Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
	1	M6 x 1.0	63	201	202	203	204	23.0 (0.907)	23.0 (0.907)
	2	M8 x 1.25	61	206	207	208	209	29.0 (1.14)	29.0 (1.14)
	3	M8 x 1.25	210	206	207	208	209	23.0 (0.907)	23.0 (0.907)
	4	M10 x 2.0	104	101	N/A	102	103	30.0 (1.18)	30.0 (1.18)
	5	M10 x 2.0	104	101	N/A	102	103	52.0 (2.05)	52.0 (2.05)
	6	M10 x 1.5	N/A	N/A	N/A	N/A	N/A	34.0 (1.35)	34.0 (1.35)
	Bolt hole 4 has a 1.5 mm (0.059 in) counterbore included in the 30.0 mm (1.18 in) drill

Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
procedure, refer to Thread Repair. Bolt hole 5 has a 15.5 mm (0.807 in) counterbore included in the 52.0 mm (2.05 in) drill depth. For the proper hardware and procedure, refer to Thread Repair.

Cylinder Head– Top/End Views

Thread Repair Specifications — figure 4

Cylinder Head– Top/End Views

	Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
	1	M8 x 1.25	N/A	N/A	N/A	N/A	N/A	23.0 (0.907)	23.0 (0.907)
	2	M6 x 1.0	205	201	202	203	204	23.0 (0.907)	23.0 (0.907)
	3	M10 x 1.5	420	211	212	213	214	30.0 (1.18)	30.0 (1.18)
	4	M8 x	210	206	207	208	209	23.0	23.0
			©	2023 Gene	ral Motors.	All rights re	served.

Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
	1.25						(0.907)	(0.907)
Bolt Hole 1 (Rocker Arm Supports) are not serviceable.

Cylinder Head– Intake/Exhaust Side Views

Thread Repair Specifications — figure 5

Cylinder Head– Intake/Exhaust Side Views

Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
1	M8 x 1.25	210	206	207	208	209	23.0 (0.907)	23.0 (0.907)

Hole	Thread Size	Insert	Drill	Counterbo Tool	re Tap	Driver	Drill Depth– Maximum mm (in)	Tap Depth– Maximum mm (in)
2	M6 x 1.0	205	201	202	203	204	21.0 (0.825)	21.0 (0.825)
3	M10 x 1.5	420	211	212	213	214	34.0 (1.35)	34.0 (1.35)
4	M8 x 1.25	210	206	207	208	209	29.0 (1.14)	29.0 (1.14)
5	M14x 1.25	N/A	N/A	N/A	N/A	N/A	26.0 (1.023)	26.0 (1.023)
Bolt Hole 5 (Spark Plug Port) is not serviceable.