Cylinder head (except GLA model) (Escort 3)

Features of the device

The cylinder head (Fig. 2.40) is cast from an aluminum alloy and has hemispherical combustion chambers. The volume of the combustion chambers is for GMA and GPA engines: 43.11-45.93 cm³. JPA: 53.39-56.55 cm³. LPA and LUA: 53.01-56.21 cm³. LRA and L7: 53.36-55.38 cm³. The cylinder head body is bored for tappets and valve bushing guides and for camshaft support bushings, and valve seats are pressed into it. The diameter of the holes for the tappets is 22.235-22.265 mm. The cylinder head gasket is installed with the "Top" mark facing the head (with the edging of the holes facing the cylinder block). The gasket designation for GMA and GPA engines is 81 SM-6051-N₂D; 81 SM-6051-N3D; JPA, LPA, LUA, LRA and L7 - 81 SM-6051-R2D; 81 SM-6051-R3D.

Valve seats

The valve seats have a working chamfer angle of 45°, the upper chamfer angle: nominal 18° (30° for LRA and L7 engines). repair 15°; lower chamfer: nominal 77-70°, repair 75-70°. Seat width 1.75-2.32 mm.

Guide bushings

Valve guide bushings are made of special cast iron and pressed into the cylinder head. Diameter of the holes of the intake and exhaust valve guide bushings: nominal size 8.063-8.094 mm, repair size with an increase of 0.2 and 0.4 mm.

Valves

The valves are made of special steel and are installed at an outward angle on both sides of the camshaft; are driven by the camshaft through hydraulic tappets and rocker arms, as a result of which there are no gaps in the valve drive mechanism (the L7 engine has mechanical tappets) (Fig. 2.40).





The valve springs are the same for the intake and exhaust valves. The height of the spring in a free state is 47.2 mm. With the valve open 27.7 mm, with the valve closed 37.084 mm. The compression force of the spring with the valve open is 85.33-93.21 kgf. With the valve closed 40.14-44.16 kgf. The valve rocker arms are stamped from steel and are fastened with one bolt each. The hydraulic (except for the L7 model) tappets are hollow, made by drawing from a steel blank. The diameter of the tappets is 22.25 mm. The diameter of the holes for the tappets in the cylinder head is 22.235-22.265 mm.

Adjusting clearances in the valve drive mechanism of the L7 engine

This operation is performed on a cold engine. The clearance between the adjusting washer and the valve end is 0.15 mm for inlet valves and 0.30 mm for outlet valves and is adjusted with a special pin key. Since the adjusting screws 1 (Fig. 2.41) are made of a very hard material, if their rotation is difficult, the pin key can break.



Therefore, it is necessary to unscrew the screw from the pusher, clean its thread, screw it in again, install the pusher and rocker arm in place and adjust the gap. When installing the rocker arms, replace the self-locking nuts with new ones. Catalog numbers for the pin key 9059235, fork key 9059226.

Removal and installation of cylinder head of GMA, GPA, JPA, LPA and LUA engine models

Disconnect the wire from the negative terminal of the battery and remove the air filter. Disconnect the lower hose from the radiator and drain the coolant into a prepared container. Disconnect the hoses from the radiator, thermostat housing and from the automatic starting device. Remove the clamp, disconnect the throttle cable and remove it together with the mounting bracket to the carburetor. Disconnect the fuel pump and brake booster hose from the intake manifold. Disconnect the electrical wires from the electric fan switch, ignition coil, coolant temperature sensor and from the electromagnetic shut-off valve. Remove the heat-insulating shield and disconnect the muffler pipe from the exhaust manifold. Loosen the generator mount and remove the drive belt. Remove the camshaft drive toothed belt cover by unscrewing the four bolts and loosen the two belt tensioner bolts.



Move the belt tensioner to the left, tighten its mounting bolts and remove the toothed belt. Disconnect the high-voltage wires, remove the distributor cap and unscrew the spark plugs. Remove the crankcase ventilation hose from the pipe on the cylinder block, unscrew the nine bolts and remove the cylinder head cover. Unscrew the cylinder head mounting bolts in the reverse order of their tightening (Fig. 2.42). Remove the cylinder head together with the intake manifold and exhaust manifold.



Before installing the cylinder head, make sure that the installation bushings are present and install the cylinder head gasket with the inscription facing up. While turning the crankshaft, set the piston of the first cylinder to a position 2 cm below TDC to avoid damaging the valves. Install the cylinder head and tighten the new mounting bolts in four stages (Fig. 2.42).



Tightening torque: 1st step 2.5 kgf·m, 2nd step 5.5 kgf·m; then turn it 90° and turn it 90° again.



Install the toothed pulleys of the crankshaft and camshaft according to the marks in their original position and put on the toothed belt of the timing mechanism drive (see the section "Camshaft"). Apply sealant (according to the Ford specification A 70 SX 19554-BA) in the form of a bead 2-3 cm long to the mating surface of the cylinder head on the side of the timing mechanism drive and on the carburetor side. Install a new cover gasket on the cylinder head and tighten the cover mounting bolts to a torque of 0.6-0.8 kgf·m.

Install the front timing belt cover, accessory drive belt and tighten it. Screw in the spark plugs, install the distributor cap and high-tension wires. Install the bracket and throttle cable. Connect the wire to the coolant temperature sensor. Connect the wires of the ignition coil, electric fan switch and electromagnetic shut-off valve. Install the brake booster and carburetor fuel supply hoses. Install the exhaust manifold with a new gasket and heat-insulating shield. Connect the cooling system hoses and fill the system with coolant.

Install the air filter and connect the battery. Check the ignition timing and idle speed. The intake manifold and exhaust manifold of the LRA and L7 engines have their own characteristics, so the removal and installation of the cylinder head of these engines differs from those described above. Disconnect the wire from the negative terminal of the battery. Remove the crankcase ventilation hose. Remove the air filter and vacuum hose from the intake manifold. Remove the air pipe connecting the metering distributor to the throttle body.



Disconnect the wires from the starting injector, control pressure regulator, thermal time relay, additional air supply valve and the ground jumper of the electromagnetic shut-off valve on the throttle body. Remove the fuel supply hoses to the control pressure regulator, starting injector and metering distributor. Disconnect the vacuum hose from the shut-off valve. After removing the hose from the control pressure regulator, disconnect the crankcase ventilation hose from the cylinder head cover, disconnect the hose from the thermostat housing and remove the injector mounting brackets. After disconnecting the brake booster hose from the intake manifold, disconnect the wires from the coolant temperature sensor and from the fuel metering distributor. The cylinder head can be removed after its temperature has dropped to the ambient temperature. The cylinder head is installed in the reverse order of its removal; the injector mounting brackets and the receiver are installed after the intake manifold and exhaust manifold are installed.

Disassembly and assembly of the cylinder head

Place the cylinder head on two wooden supports to avoid damaging the valves. Remove the exhaust manifold and intake manifold together with the carburetor. Remove the ignition distributor and thermostat housing. Using a screwdriver, lock the camshaft toothed pulley and unscrew its mounting bolt (Fig. 2.43).



Remove and lay out in order the rocker arms with guides and thrust bushings. Compress the valve springs with device 21.097 (Fig. 2.44), remove the crackers, release the device and remove the upper plates, springs and support washers of the valve springs.





Remove the oil seals using a screwdriver (Fig. 2.45) and take out the valves.



Remove and lay out the tappets in order. Unscrew the bolts securing the camshaft thrust flange and carefully remove the camshaft toward the ignition distributor. Unscrew the coolant temperature sensor and the heater hose branch pipe. If necessary, unscrew the studs securing the intake and exhaust manifolds.

Before assembling the cylinder head, it is necessary to check the clearance between the valves and the guide bushings and the condition of the working chamfers of the valve seats. To do this, insert the valves into the guide bushings and determine the clearance value using a dial indicator. If the obtained result exceeds 0.020-0.063 mm for intake valves and 0.046-0.089 mm for exhaust valves, it is necessary to ream the holes in the bushings to the next repair size (see Table 2.6) using reamers 21.071-21.074. The tool must be inserted from the combustion chambers. Then it is necessary to countersink the valve seats with a special cutter, observing the angles specified above. After countersinking, grind the working chamfers and lap the valves. Thoroughly clean the head, blow out the guide bushings and valve seats with compressed air. Scratches and burrs on the working chamfers of valves and seats are not allowed.





Screw in the intake and exhaust manifold mounting studs if they were unscrewed. Install the coolant temperature sensor and the heater hose branch pipe. Lubricate the camshaft journals and support bushings in the cylinder head, as well as the thrust flange, with engine oil. Install the camshaft in the cylinder head, starting it from the rear and trying not to damage the bushings. Install the thrust flange (Fig. 2.47) and tighten its mounting bolts to a torque of 1.0-1.5 kgf·m.



Lubricate the tappets with engine oil and install them in the corresponding seats. Lubricate the valve stems with hypoid oil and install the valves in the guide bushings, install the spring support washers. Seal the grooves for the crackers on the valve stems with adhesive tape, lubricate the new oil scraper caps with oil and, using the Ford 21.007 mandrel, install the caps on the valve guide bushings. Remove the adhesive tape, install the valve springs and upper spring plates. Compress the valve springs with the 21.097 device and install the crackers for fastening the plates. Install the thrust bushings and rocker arms with their guides (Fig. 2.48), paying attention to the correct fit.



Tighten the new rocker arm mounting nuts and tighten them to a torque of 2.1-2.5 kgf·m. Using tool 21.094 and the camshaft toothed pulley mounting bolt, install the new camshaft oil seal (Fig. 2.49).



Install the camshaft toothed pulley and tighten the mounting bolt to a torque of 5.4-5.9 kgf·m. Install the thermostat housing. Replace the sealing ring under the ignition distributor and install the ignition distributor. Lubricate the fuel pump pusher with engine oil and install the fuel pump. Install the intake manifold and exhaust manifold with new gaskets.

The material was copied from an information website [FordBook]