Valve clearances
Measurement of operating clearance is carried out with the engine cold
Operating clearance
- Inlet valve: 0,50 ± 0,05 mm
- Exhaust valve: 0,50 ± 0,05 mm
Method of checking
NoteCylinder No. 1 is at the timing end
First method
| fully open | check | check |
|---|---|---|
| exhaust valve | inlet valve | exhaust valve |
| 1 | 3 | 4 |
| 3 | 4 | 2 |
| 4 | 2 | 1 |
| 2 | 1 | 3 |
For each valve note the values recorded for the clearances
Second method
| check | inlet valve | exhaust valve |
|---|---|---|
| position the valves of cylinder N°1 on the rock | 4 - 3 | 4 - 2 |
| position the valves of cylinder N°4 on the rock | 1 - 2 | 1 - 3 |
For each valve note the values recorded for the clearances
Valve clearance adjustment
(1) adjustment shim
(2) thrust pad
Clearance J is measured with the engine cold
If the clearance measurements J are not correct, carry out the following operations
- Measure the thickness "E" of the adjustment shim (1)
- Determine the thickness of adjustment shims (1) to be fitted by referring to the example (column A or B)
| - | A | B |
|---|---|---|
| operating clearance | 0,50 mm | 0,50 mm |
| clearance measured "J" | 0,35 mm | 0,70 mm |
| difference | - 0,15 mm | + 0,20 mm |
| thickness "E" | 3,80 mm | 3,70 mm |
| shims to be fitted | 3,65 mm | 3,90 mm |
| clearance obtained | 0,50 mm | 0,50 mm |
Key
- A: clearance "J" smaller than operating clearance
- B: clearance "J" greater than operating clearance
Valve timing chart
Diagram with a theoretical valve clearance of 0,8 mm
| Before Top Dead Centre | 8° |
|---|---|
| After Bottom Dead Centre | 37° |
| Before Bottom Dead Centre | 48° |
| After Top Dead Centre | 8° |