Pistons and Cylinder Codes

Code for piston on piston crown

Code for piston on piston crown

Cylinder Codes (Numbers)

Porsche 928 Motorsport
Firing Order 1-3-7-2-6-5-4-8

Code for cylinder on engine block

Code for cylinder on engine block

a - Cylinder code (location) b - Tolerance group

Notes for Installing Pistons (32-valve engines)

The "AV -" (exhaust valve) inscribed on the base of the piston indicates the installation position (arrow toward exhaust side).

The valve cutouts for the valves are of equal size on both sides. The installation position is indicated by an arrow which points toward the belt pulley.

Valve Dimension Engine Type M 28.21/22

Size

Intake

Exhaust

a

45,00 mm

40,00 mm

b

8,97 mm

8,95 mm

c

110.50 mm

110,90 mm

a

45"

45'

Reconditioning Valve Seats

Reconditioning Valve Seats

Diagram Valve Seat Reconditioning

Valve seats can be machined up to the wear limit point, distance "A" =14,5 mm, (new size is 13,65 ± 0,45).

Check with a new valve. Distance "A" must not be exceeded, since otherwise the function of the hydr. valve followers could not be guaranteed.

Angles and Dimensions of Valve Seat Inserts

Angles and Dimensions of Valve Seat Inserts

Installed Length and Colour Code of Valve Springs colour code - 2 or 3 white lines -Intake valve 41,0 + 0,5 mm

Exhaust valve 40,0 + 0,5 mm

Check installed length with special tool 9138/1 and correct by installing or removing shims if necessary.

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