Valve guides

Make

Alfa Romeo

Model

145/146 Factory Service Manual

Year

1994–1999

Section

Engine › Valve guides

Technical data and maintenanceValve guides

Unit: mm
Diameter of valve guide seats "a"	12.000 ÷ 12.018
Valve guide protrusion "b"	10.35 ÷ 10.65
Minimum permissible height after refacing "c"	≥ 127.8
Maximum error of flatness of head lower surface	0.03
Diameter of camshaft journals "d"	27.000 ÷ 27.033
Diameter of valve cup seats "e"	33.000 ÷ 33.025
Cylinder head heating temperature for fitting valve seats	100° ÷ 120°C

Valve guides

Unit: mm
Outside diameter of valve guides "a"	Intake	12.040 ÷ 12.051
	Oversize 0.2	12.240 ÷ 12.251
	Exhaust	12.050 ÷ 12.068
	Oversize 0.2	12.250 ÷ 12.268
Inside diameter of valve guides "b"		7.000 ÷ 7.015
Interference between valve guides and their seats	Intake	0.022 ÷ 0.051
	Exhaust	0.032 ÷ 0.068

Valve seats

Unit: mm
Outside diameter of valve seats	Intake	34.100 ÷ 34.116
	Oversize 0.2	34.300 ÷ 34.316
	Exhaust	28.096 ÷ 28.116
	Oversize 0.2	28.296 ÷ 28.316
Reference diameter ØR	Intake	31.0
	Exhaust	24.5
Limit for refacing valve seat upper section "a"	Intake	0.4
	Exhaust	1.1
Limit for refacing valve seat contact area	Intake "R"	0.9
	Exhaust "b"	1.1
Upper valve seat taper limit "α"	Intake	150°
	Exhaust	120°
Valve seat contact area taper "β"		90° ± 20'
Inner valve seat taper limit "γ"	Intake	75°
	Exhaust	60°

(1) Origin profile

(2) Profile after maximum reconditioning

02 Maintenance