Cylinder Head - Top View

Fig 1: Cylinder Head Thread Repair - Top View

Courtesy of GENERAL MOTORS CORP.

Service Hole Location	Thread Size	Drill	Counterbore Tool	Stop Collar	Tap	Driver	Insert	Drill Depth (Max)		Tap Depth (Min)
J 42385-400								mm	(in)	mm	(in)
1	M 6 x 1	405	n/a	406	203	204	205	28	1.103	24	0.945
2	M 6 x 1	201	202	n/a	203	204	205	22	0.866	18	0.709
3	M 6 x 1	405	n/a	407	203	204	205	THRU		THRU