Porsche 928 Workshop Manual page 207

15
Engine/Cylinder Head, Valves
928
t3
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10. Valve seat inserts must be machined
after replacing valve guides.
Grinding in valves with grinding paste
will not be sufficient.
9. If absolutely necessary, valve guides can be
reamed out with Special Tool 3015.
Procedures:
Always ream out valve guides with
"petroleum" as a lubricant. Back out
reamer frequently to remove burrs. Check
reamed bore with limit gauge P 206 and,
if necessary, ream out bore again with a
dry reamer.
a
15-30
Replacing Valve Guides
Printed in Germany