Porsche 912 E - Valve Machining and Refacing

15
Engine, Cylinder Head, Valves
MACHINING INTAKE VALVES
c
Intake Valve
Exhaust Valve
a
41.8-42.2 mm dia.
35.8-36.2 mm dia.
b 7.94-7.95mm dia.
8.91-8.92 mm dia.
c 116.8 mm 117mm
45° 45°
caution
Exhaust valves must not be turned. Only
grinding in is permissible.
When grinding in valves, frequently
lift and
turn valve
to avoid scoring.
15
- 6
Machininl! Valves Refac.ino V.olvP ~P"t•
REFACING VALVE SEATS
Valve seats showing wear or burnt spots can be
refaced as long as the permissible seat width
0
can be maintained and the 15 chamfer at its
outer
circumference does not exceed the out-
side diameter of the valve seat insert. If it
does, replace cylinder head with a new or
overhauled
unit. The valve seat inserts cannot
be replaced with conventional shop tools
because
the inserts are (cold) shrunk in.
Valve Seat Width (a)
Intake
1.8 - 2.2 mm
Exhaust 2.0 - 2.5 mm