For compensation of thermal expansion of the valve the gap between an end face of a core of the valve and a cam of the camshaft is structurally set. At the increased gap the valve will not open completely, and at reduced — completely to be closed.

Fig. 5.9. Measurement of a gap in the valve drive: and – the measured gap

The gap and (fig. 5.9) measure by the probe on the cold engine (at a temperature of +20 °C) between a camshaft cam (the cam has to be directed up from a pusher) and a valve pusher. The nominal gap for the inlet valve makes 0,17–0,23 mm, for final – 0,31–0,37 mm. Gaps regulate selection of thickness of pushers. In spare parts deliver sets of pushers of different thickness.

Concerning a belt of the drive of the gas-distributing mechanism the valves located on the right – final, at the left — inlet.

It will be required to you: all tools necessary for removal of camshafts (see. "Replacement of camshafts"), and also set of flat probes.

1. Install the piston of the first cylinder in the provision of VMT of a step of compression (see. "Installation of the piston of the first cylinder in the provision of VMT of a step of compression").

2. Uncover a head of the block of cylinders (see. "Replacement of laying of a cover of a head of the block of cylinders").

3. Measure by the probe a gap and (see fig. 5.9) between cams of both camshafts and pushers of valves. Write down the measured gaps.

4. Turning a bent shaft for a bolt of fastening of its pulley every time on 180 °, measure and write down gaps at valves of other cylinders. Operating procedure of cylinders: 1–3–4–2. It is necessary to replace pushers of those valves at which gaps differ from nominal. After measurement of all gaps install the piston of the 1st cylinder in the provision of a step of compression.

5. Remove camshafts (see. "Replacement of camshafts").	6. Take a pusher of the valve from which adjustment of a gap is required from a nest of a head of the block of cylinders, and write down its thickness (it is specified on its reverse side).

Note The number applied on a valve pusher is the thickness of a pusher. However only three figures after a comma are put (for example, "650" means thickness of a pusher of 3,650 mm).

7. Calculate thickness of a new pusher by a formula (all values in mm)

H = B+A–C, where

A — value of the measured gap;

B — thickness of an old pusher;

With — a nominal gap;

H — thickness of a new pusher.

8. Establish a new pusher into place.

9. Similarly replace pushers of all valves from which adjustment of a gap is required.

10. Install camshafts, but do not establish a belt of the drive of the gas-distributing mechanism yet.

11. Turning camshafts for the hexagons executed on them, measure by probes the received gaps. If gaps differ from nominal rates, repeat adjustment (see subitem 6-8).

12. If all gaps correspond to nominal rates, turn camshafts so that cams of the drive of valves of the 1st cylinder were established, as shown in fig. 5.9.

13. Establish a belt of the drive of the gas-distributing mechanism and all removed details as it should be, the return to removal.