Replacing Valve Guides

Replacing valve guides if necessary, must be done before valve seat and face are ground since the valve stem hole in valve guide is the basis from which all face and seat grinding is done. Valve stem-valve guide clearance is as follows: Exhaust valves, .004 in. to .006 in. loose; intake valves, .002 in. to .004 in. loose. If valve stems and/or guides are worn to exceed the maximum tolerances by more than .002 in., new parts must be installed.

1. Overhead oil feed line

3. Feed line rubber sleeve (3)

4. Cylinder interconnecting oil line

5. Hpad bolt and washer (5)

8. Spring cap retainer (2)

9. Cylinder head

10. Cylinder head gasket

11. Rocker housing nut and washer (5)

12. Oil feed line nipple

13. Rocker arm housing

14. Rocker housing gasket

15. Rocker arm shaft acorn nut and washer

16. Rocker arm spacer (2)

17. Rocker arm shaft (2)

18. Rocker arm shaft screw and O-ring (2 each)

19. Rocker arm bushing (4)

21. Valve seat insert (one exhaust, one intake)

22. Rocker housing stud (8)

24. Upper valve spring collar (2)

25. Outer valve spring (2)

26. Inner valve spring (2)

27. Lower spring collar (2)

28. Valve (one exhaust, one intake)

29. Valve guide (one exhaust, one intake)

30. Heli-coil spark plug insert (1974 & earlier)

31. Nut

32. Washer

33. Upper engine mounting bracket

Tap out valve guides with shouldered drift pin (from chamber side) and insert replacement guide on arbor press. Be particularly careful to press replacement guide squarely into hole.

New valve guides are reamed to correct size. However, when guides are pressed into cylinder heads, they may close up slightly; also the ends may be burred. Therefore, after new guides are in place, they should be sized and cleaned with an expansion reamer.

K is of prime importance that valve guides fit tightly in cylinder heads, or valves may not seat properly. If original guide or new standard guide is not a tight press fit, an oversize guide must be installed. Oversize guides can be obtained .001 in. to .008 in. oversize. The number of grooves on O.D. indicates number of thousandths of an inch press diameter is oversize.

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