Installing Valve Seat Inserts

	Valve Seat Insert	Outside Diameter of Valve Seat Insert Intake & Exhause d1	Bore Diameter in Cylinder Head Intake & Exhaust D1
1969-Models		mm	mm
911 T and E
Standard	Intake	45.180 - 45.164	45.000 - 45.025
1st oversize	Intake	45.500 - 45.484	45.320 - 45.345
911 S
Standard	Intake	47.180 - 47.164	47.000 - 47.025
1st oversize	Intake	47.500 - 47.484	47.320 - 47.345
911 T, E, and S
Standard	Exhaust	41.200 - 41.184	41.000 - 41.025
1st oversize	Exhaust	41.760 - 41.744	41.560 - 41.585
1970-Models
911 T-C, E-C, and S-C
Standard	Intake	48.180 - 48.164	48.000 - 48.025
1st oversize	Intake	48.500 - 48.484	48.320 - 48.345
Standard	Exhaust	42.200 - 42.184	42.000 - 42.025
1st oversize	Exhaust	42.760 - 42.744	42.560 - 42.585