NOTE At repair of engines with leaky valves process or to replace saddles of valves and valves insufficiently. Especially in engines with long service life it is necessary to check directing plugs of valves on wear.

Saddles of valves follows дообрабатывать only so to reach a faultless type of a working surface. Before processing follows риссчитать the most admissible allowance on processing. At allowance excess on processing function of hydraulic regulation of a gap in a drive of valves (hydrojacks) that will cause GBTs replacement can be broken.

Remove cam-shafts.

Calculate the most admissible allowance on processing as follows:

– insert the valve in directing and densely press it to a saddle;

NOTE If the valve at repair is replaced, at measurements follows use the new valve.

Fig. 2.85 . A distance between the end of a core of the valve and the upper edge of a head of the block of cylinders

– measure A distance between the end of a core of the valve and the upper edge of a head of the block of cylinders (fig. 2.85) ;

– calculate the most admissible allowance on processing on the basis of the measured distance of A and minimum admissible size.

Minimum sizes

The measured distance of A minus the minimum size = Max. admissible amount of completion.

Example:

The measured distance..... 10,6 mm

Minimum size..... 10,2 mm

The most admissible allowance on processing..... 10,6–10,2=0,4 mm

NOTE On the following schemes the most admissible allowance on processing of saddles of valves is represented as the size B.

Processing of a saddle of the inlet valve

Fig. 2.86 . Scheme of processing of a saddle of the inlet valve

a–Ж30,6 mm

b–the most admissible amount of operational development

c–0,9–1,5 mm

d–Max. Ж35,0 mm

r2 – radius of 2,0 mm

Z–bottom edge of a head of the block of cylinders

a–45 ° corner of a facet of a saddle of the valve

b–30 ° a corner of the top correcting facet

g–60 ° a corner of the bottom correcting facet

Processing of a saddle of the final valve

Fig. 2.87 . Scheme of processing of a saddle of the final valve

a–Ж26, mm

b–the most admissible amount of operational development

c–1,2–1,7 mm

d–Max. Ж29,0 mm

r2 – radius of 2,0 mm

Z–bottom edge of a head of the block of cylinders

a–45 ° corner of a facet of a saddle of the valve

b–30 ° a corner of the top correcting facet

g–60 ° a corner of the bottom correcting facet