911 Carrera 2 Targa F6-3600cc 3.6L SOHC (1992)
Valve Guide: Service and Repair
REPLACING VALVE GUIDES
Removing
Working from the camshaft side, use a facing cutter to mill projecting valve guides until guides are flush with cylinder head. With a sharp blow with a
hammer, dislodge each guide and use a press to force out toward combustion-chamber side.
Installing
The holes which accommodate the valve guides in the cylinder head will have been made slightly wider by removal of the old guides. New oversize
valve guides must be installed and machined to fit (see table of sizes).
1.
Measure valve-guide holes in cylinder head.
2.
On a lathe, machine the oversize valve guides to the correct outside diameter to fit the hole in the cylinder head. The squeeze for intake and
exhaust valves must be 0.06 - 0.09 mm.
3.
Dust machined valve guides with talcum powder and, working from the camshaft side, press guides into cylinder head with improvised mandrel.
4.
With a broach or on a precision drilling bench, bore valve guides out to size "g" = 9.00 - 9.015 mm. If no other tool is available, a reamer can also
be used to enlarge the valve guides.
Important: Always set or clamp the cylinder head at the correct angle before pressing in and boring the valve guides.
After replacing valve guides, check bearing pattern on valve seat and remachine valve seat if necessary.
Table of sizes for installing valve guides:
Valve guide
Outside diameter
Hole diameter
*Valve guide
Cylinder head