The cylinder head is common to four cylinders, cast from aluminum alloy, with tent-shaped combustion chambers
Inlet and outlet channels are located on different sides of the block head.
The valves are arranged V-shaped in two rows: inlet on one side, exhaust on the other.
Ceramic valve seats and brass valve guides are pressed into the head.
The internal diameter of the guide bushings is 7±0.015 mm, the outer diameter (for bushings supplied as spare parts) is 12.079-12.090 mm and 12.279-12.290 mm (bushing increased by 0.2 mm).
The diameter of the intake valve plate is 29 mm, the exhaust valve is 25.5 mm.
The diameter of the intake valve stem is 6.975±0.007 mm, the exhaust valve is 6.965±0.007 mm.
One spring is installed for each valve.
The length of the spring in a free state is 38.19 mm, under a load of 240±9.6 N (24.5±0.98 kgf) it should be 32 mm, and under a load 550±27.5 N (56.1± 2.8 kgf) - 24 mm.
The valves are actuated by the camshaft cams through cylindrical hydraulic pushers located in the guide holes of the cylinder head along the axis of the valve holes.
Hydraulic tappets automatically eliminate the gap in the valve mechanism, so when servicing the car there is no need to check and adjust the gap in the valve mechanism.
Oil for operating the hydraulic tappets is supplied from the lubrication system through a vertical channel in the cylinder block to a channel in the cylinder head near the 5th mounting bolt, and then through the upper channels made on the lower plane of the bearing housing.
The same ropes supply oil to lubricate the camshaft journals.
In the vertical channel of the cylinder head there is a check ball valve that prevents oil from draining from the upper channels after the engine is stopped.
Two camshafts are used to drive the valves: intake and exhaust.
The shafts are cast from cast iron and are equipped with five bearing journals, which rotate in sockets made in the cylinder head and in one common camshaft bearing housing.
To increase wear resistance, the working surfaces of the cams and the neck under the oil seal are bleached.
In order to distinguish the intake camshaft from the exhaust camshaft, a distinctive band "A" is made on the intake shaft near the first support.
The shafts are kept from axial movements by thrust collars located on both sides of the front support.
The front ends of the camshafts are sealed with self-clamping rubber seals.
The rear holes, located along the axis of the shafts in the cylinder head and bearing housing, are closed with rubberized cap plugs.
Also look at the articles:
- “Repair of cylinder head VAZ-21126”;
