Reconditioning

NOTE: Special Tools Required: 5027, 5028, 5029, 5160, 5218, 5220, 5224.

REPAIR PROCEDURES:

Replacing Valve Guides:
1. Heat cylinder head to 100 ±10 C (212 ±18 F).

Valve Guide Removal:

2. Use drift 5218 to press out guides. Press toward the combustion chamber.
3. Make sure guide has not seized during removal. If so valve guide bore must be reamed to oversize.

Valve Guide Reamers:

Valve Guide:

- Use Valve Guide,they are marked with grooves. Make sure the new guide has the same number of grooves as the old guide.

No. of grooves Size
0 Standard
1 Oversize 1
2 Oversize 2
3 Oversize 3

Valve Guide Installation:

4. Press in new valve guide:
- Cylinder head should be at room temperature.
- Use drift 5027 for intake valves and drift 5028 for exhaust valves.
5. Press in guide until drift contacts cylinder head to obtain correct height.
CAUTION: Press force must be at least 9000 N (2000 lbs.) if press force is lower, the guide must be removed. Ream guide seat to next oversize and press in guide of corresponding size.

Part Numbers for valve guide reamers:

Oversize Reamer
1 5161
2 5162
3 5163

Tool #5224, Reamer:

6. Clean inside of valve guide:
- Use reamer 5224.
- Also reamer 5164 can be used.

NOTE: Valve and seat must be ground in after replacing valve guide.

Replacing Valve Seats:

Valve Seat Removal Step #1:

1. Cut two notches in old valve seat:
- This reduces valve seat tension.
2. Grind an additional notch in valve seat to obtain starting point for chisel acc.
- Be careful not to damage cylinder head.

Valve Seat Removal Step #2:

3. Split valve seat:
- Use a chisel to split valve seat.
- Be careful when handling chisel.

Valve Seat Removal Step #3:

4. Tap out old valve seat:
- Use a long drift, passing through cylinder head channel.
5. Check valve seat recess:
- If damaged, ream recess to next oversize.

Valve Seat Recess Measurement Step #1:

6. Measure diameter of valve seat recess:
- Use an inside micrometer.

Valve Seat Measurement Step #2:

7. Measure new valve seat:
- New valve seats are not marked for size and must be measured. Two oversizes are available.
- Valve seat should be 0.17 mm (0.0067 in) larger than recess in cylinder head.

Valve Seat Cutter:

8. If grip is less than 0.17 mm (0.0067 in):
- Recut valve seat to oversize.
- Use valve seat cutter, for instance MIRA P/N 998 6045-5. Follow manufacturer's instructions.

Valve seat diameter:
Standard
Intake: 46.00 mm (1.8110 in)
Exhaust: 38.00 mm (1.4960 in)
Oversize 1
Intake: 46.25 mm (1.8209 in)
Exhaust: 38.25 mm (1.5059 in)
Oversize 2
Intake: 46.50 mm (1.8307 in)
Exhaust: 38.50 mm (1.5157 in)

Heating Cylinder Head:

9. Heat cylinder head to 100°C (212°F).
10. Install new valve seat on drift:
- Use drift 5029 for intake valve seat and drift 5220 for exhaust valve seat.

Cooling Valve Seat:

11. Cool seat to -7O°C (-94°F)
- Use carbon dioxide or similar agent.
- Wear protective gloves for safety.

Valve Seat Installation:

12. Tap valve seat into cylinder head:
- This operation must be carried out very quickly, within 3-4 seconds, to avoid temperature loss.
13. Check seat fit:
- Seat should bottom and sit secure. If not, oversize seat must be used.

NOTE! After replacing, valve seat must be ground and valve ground in.

IMPORTANT! Stellite Coated Valves:

Valve Seat Angle & Width:

Grinding Valves And Valve Seats:

CAUTION: Valves are stellite coated and must not be machined. They can only be ground-in with lapping paste against valve seat, If machined, the stellite coating is removed, and the valves lose part of their heat resistance.

1. Mill or grind valve seats:
- Same angle for intake and exhaust valve seats.

Valve seat width:
Intake 1.3-1.9 mm (0.051-0.075 in)
Exhaust 1.7-2.3 mm (0.967-0.091 in)

2. Check valve fit on valve seats:
- If necessary, grind valves with lapping paste.