Cylinder head

Make

Alfa Romeo

Model

145/146 Factory Service Manual

Year

1994–1999

Section

Engine › Cylinder head

Technical data and maintenanceCylinder head

CYLINDER HEAD

Head

	Unit: mm
Diameter of valve guide seats "a"	13.950 ÷ 13.977
Diameter of valve cup seats "b"	37.000 ÷ 37.025
Diameter of valve seat housings	Intake "c" 38.989 ÷ 39.014
	Exhaust "d" 34.989 ÷ 35.014
Diameter of camshaft centre bearings	Second "e" 25.545 ÷ 25.570
	Third "f" 24.045 ÷ 24.070
Diameter of camshaft side bearings "g"	43.020 ÷ 43.040
Width of third camshaft bearing shoulder "h"	18.950 ÷ 19.030
Precombustion chamber protrusion or undercut in relation to the cylinder head surface "i"	- 0.765 ÷ + 0.055

Valve guides

	Unit: mm
Outside diameter of valve guides "a"	14.040 ÷ 14.058
	Oversized by 0.20
Inside diameter of valve guides (bore) "b"	8.022 ÷ 8.040
Interference between valve guides and seats	0.063 ÷ 0.108

Valve seats

	Unit: mm
Outside diameter of valve seats "a"	Intake 39.095 ÷ 39.110
	Exhaust 35.085 ÷ 35.100
Valve seat taper "α"	45° ± 5'
Length "L" of valve seat section with taper at 45°	~ 2.7
Interference between valve seats and housings	Intake 0.081 ÷ 0.121
	Exhaust 0.071 ÷ 0.111
Cylinder head heating temperature for fitting valve seats	80° ÷ 100°C

Valves

	Unit: mm
Diameter of valve stems "a"	Intake 7.974 ÷ 7.992
	Exhaust
Diameter of valve mushrooms "b"	Intake 37.300 ÷ 37.600
	Exhaust 33.300 ÷ 33.600
Valve mushroom angle "α"	Intake 45°30' ± 7'
	Exhaust
Radial clearance between valve stems and guides	Intake 0.030 ÷ 0.066
	Exhaust

02 Maintenance