4.6.1. General information and sizes of details

In engines the 16-valvate mechanism of gas distribution with two camshafts located in a head of the block of cylinders is used. The drive of shaft is carried out from a bent shaft by two roller chains on GA14DE and GA16DE engines, one roller chain on the SR20DE engine.

The head of the cylinder is cast from aluminum alloy, has four valves on the cylinder; combustion chambers of a hemispherical form. In a head of the block of cylinders saddles and the directing plugs of valves are pressed. Cases of bearings of camshafts are processed for a single whole with a head of the block of cylinders and have removable covers. The correct provision of a head on the block of cylinders is fixed by two adjusting plugs.

Fig. 2.13. Details of the mechanism of gas distribution of GA14DE and GA16DE engines: 1 — a pulley of a bent shaft; 2 — a boot of a natyazhitel; 3 — laying; 4 — a natyazhitel of a chain of the drive of an intermediate asterisk; 5 — an asterisk of the inlet camshaft; 6 — a natyazhitel of a chain of the drive of camshafts; 7 — an asterisk of the final camshaft; 8 — a chain of the drive of camshafts; 9 — the camshaft of inlet valves; 10 — the camshaft of final valves; 11 — an adjusting washer; 12 — a pusher; 13 — crackers; 14 — a plate of a spring; 15 — a spring; 16 — a maslootrazhatelny cap; 17 — a basic washer of a spring; 18 — the valve; 19 — an axis of an intermediate asterisk; 20 — an intermediate asterisk; 21 — an uspokoitel; 22 — the purpose of the drive of an intermediate asterisk; 23 — an asterisk of a bent shaft; 24 — the plug of the drive of the oil pump; 25 — a forward cover of the drive of camshafts

Fig. 2.14. Details of the drive of the mechanism of gas distribution of the SR20DE engine: 1 — an asterisk of the inlet camshaft; 2 — a bolt of fastening of the top guide of a chain; 3 — camshafts; 4 — the top guide of a chain; 5 — a sealing ring; 6 — the block of cylinders; 7 — an asterisk of the final camshaft; 8 — a bolt of fastening of an asterisk of the camshaft; 9 — a chain of the drive of camshafts; 10 — a forward guide of a chain; 11 — an asterisk of a bent shaft; 12 — a bolt of fastening of a forward guide of a chain; 13 — the plug of the drive of the oil pump; 14 — a bolt of fastening of a cover of the drive of camshafts; 15 — a pulley of a bent shaft; 16 — a bolt of fastening of a pulley of a bent shaft; 17 — a cover of the drive of camshafts; 18 — a pin bolt; 19 — laying; 20 — a sealing ring; 21 — a natyazhitel of a chain; 22 — a bolt and a nut of a natyazhitel of a chain; 23 — a boot of a natyazhitel

Treat the mechanism of gas distribution: the head of the block of cylinders, camshafts, inlet and final valves, springs of valves with details of their installation directing plugs of valves, hydraulic pushers or pushers with adjusting washers, levers, driving chains, asterisks, natyazhitel of driving chains (fig. 2.13 and 2.14).

Height of a head of the block of cylinders of GA engines is measured between the surface of interface to the block of cylinders and the basic plane of bolts of fastening of a head and makes 117,8 — 118,0 mm.

Height of a head of the block of cylinders of SR engines is measured between the interfaced surfaces of a head and has to make 136,9 — 137,1 mm.

Tolerance from planeness of a surface of interface to the block of cylinders no more than 0,1 mm. When grinding this surface metal removal no more than 0,2 mm is allowed.

The pig-iron directing plugs of valves are pressed in a head of the block of cylinders. The tightness at a press fitting of plugs in a head of the block of cylinders makes 0,024 — 0,059 mm.

Diameter of openings in a head of the block of cylinders for a press fitting of the directing plugs, mm:

new       9,475 — 9,534

repair       9,723 — 9,734

Gap between a core of the valve and the directing plug for inlet valves of 0,02 — 0,05 mm, for final valves of 0,04 — 0,07 mm.

Vystupaniye of the directing plugs of valves of 11,5 — 11,7 mm.

Steel saddles of valves are pressed in a head of the block of cylinders.

Diameter of openings in a head of the block of cylinders for a press fitting of repair saddles of valves, mm:

inlet:

       GA14DE 30,500 — 30,516 engine

       GA16DE 31,500 — 31,516 engine

final:

for all       engines 25,500 — 25,516

Dimensional characteristics of saddles of valves of GA engines are presented in tab. 2.5.

Characteristic	Inlet valves	Final valves
Width of a working facet, mm	1,06-1,34	1,20-1,68
Outer diameter of a working facet, mm	29,5-29,7	23,5-23,7
Internal diameter of a working facet, mm	27,8-28,0	-
Corner of a working facet	45 °	-
Corner of the top facet	30 °	15 °
Corner of the lower facet	60 °	-

Laying of a head of the block of cylinders is made of synthetic material (without the content of asbestos), has a silicone plait on perimeter and a metal fringing

openings around cylinders. Laying is established by mark "TORAHS" towards a head of the block of cylinders.

On GA14DE and GA16DE engines the mechanical pushers of a cylindrical form moving in openings of a head of the block of cylinders are applied. On the top part of pushers there is a dredging for installation of an adjusting washer. Outer diameter of pushers is 29,960 — 29,975 mm. Diameter of openings in a head of the block of cylinders of 30,000 — 30,021 mm. A gap between a pusher and a wall of an opening in a head of the block of cylinders of 0,025 — 0,061 mm.

On the SR20DE engine the hydraulic pushers ensuring bezzazorny functioning of the mechanism of gas distribution are established. Outer diameter of hydropushers is 16,980 — 16,993 mm. Diameter of openings in a head of the block of cylinders of 17,00 — 17,02 mm. A gap between a pusher and a wall of an opening in a head of the block of cylinders of 0,07 — 0,04 mm.

Four steel valves (two inlet and two final) given by camshafts through pushers are installed in each combustion chamber. Dimensional characteristics of valves of GA engines are presented in tab. 2.6.

Engine	Inlet valves	Final valves
Total length of the valve, mm
GA14DE and GA16DE engines	92,0-92,5	92,37-92,87
SR20DE engine	101,19-101,6	102,11-102,5
Diameter of a core of the valve, mm
GA14DE and GA16DE engines	5,465-5,480	5,445-5,460
SR20DE engine	5,965-5,980	36,945-6,960
Diameter of a cylindrical part of a plate of the valve, mm
GA14DE engine	28,9-29,2	23,9-24,2
GA16DE engine	29,9-30,2	23,9-24,2
SR20DE engine	34,0-34,2	30,0-30,2
Corner of a working facet of the valve
All engines	45 °15 '-45 °45'
Minimum admissible thickness of a cylindrical part of a plate of the valve, mm
All engines	0,9-1,1

On the maslootrazhatelny caps directing plugs of valves of a napressovana. On each valve one spring identical to inlet and final valves is established.

Spring length in a free state:

— GA14DE engines and       GA16DE 41,19 mm;

—       mm SR20DE 49,36 engine.

Spring length under loading of 34,5 kg has to be equal to 25,26 mm.

The most admissible not coaxiality of rounds of springs:

— for GA14DE engines and       GA16DE 1,8 mm;

— for       the mm SR20DE 2,2 engine.

Camshafts are manufactured of cast iron, inlet shaft — five-basic, final — six-basic.

Height of cams of engines of camshafts makes:

— for the GA14DE engine: 39,38 — 39,57 mm;

— for the GA16DE engine: 39,38 — 39,57 mm for a shaft of inlet valves: 39,88 — 40,07 mm for a shaft of final valves;

— for the SR20DE engine: 28,408 — 38,598 mm for a shaft of inlet valves; 37,92 — 38,11 mm for a shaft of final valves.

The most admissible wear of cams of 0,2 mm.

Gaps in the mechanism of the drive of valves of GA engines on the hot / cold engine make, mm:

inlet valves 0,32 — 0,40/0,25 — 0,33;

final valves 0,37 — 0,45/0,32 — 0,40.

Diameter of basic necks of camshafts, mm:

GA14DE and GA16DE engines:

neck No. 1 (from the camshaft drive)       27,935 — 27,955

necks No. 2 —       5 23,935—23,955

       SR20DE 27,935 — 27,955 engine

Radial gap of camshafts, mm:

nominal       0,045 — 0,086

the most admissible       0,15

Axial gap of camshafts, mm:

GA14DE and GA16DE engines:

nominal       0,070 — 0,143

the most admissible       0,2

SR20DE engine:

nominal       0,055 — 0,139

the most admissible       0,2

Fig. 2.15. Marking of camshafts: 1 — the camshaft of inlet valves; 2 — the camshaft of final valves

On camshafts of inlet valves marking of "I", final valves — "Е" is put (fig. 2.15).

Fig. 2.16. Order of installation and marking of covers of cases of bearings of camshafts: 1 — number of a cover; 2 — the arrow directed towards the drive of camshafts

Numbering of covers of camshafts is given in fig. 2.16.

Phases of gas distribution of GA engines are specified in tab. 2.7 without a gap between cams of camshafts and pushers.

Characteristic	Engine model
	GA14DE	GA16DE
The beginning of opening of the inlet valve to release step VMT, an advancing	0 °	0 °
Closing of the inlet valve after compression step NMT, delay	34 °	34 °
The beginning of opening of the final valve to NMT of the working course, an advancing	38 °	42 °
Closing of the final valve to release step VMT, an advancing	4 °	0 °

The drive of camshafts on GA engines is carried out from a bent shaft by two chains. One chain having 80 links rotates an intermediate asterisk, the second, having 54 links, gives rotation of an intermediate asterisk to camshafts. Camshafts of the SR20DE engine are given by one roller chain. Chains stretch hydraulic natyazhitel.