SOHC engines

General information

The engine is of a four-cylinder, in-line, single overhead camshaft type, mounted at the front of the vehicle and available in 1.3, 1.6, 1.8 and 2.0 litre versions.

The crankshaft incorporates five main bearings. Thrustwashers are fitted to the centre main bearing in order to control crankshaft endfloat.

The camshaft is driven by a toothed belt and operates the slightly angled valves via cam followers which pivot on ball-pins.

The auxiliary shaft which is also driven by the toothed belt, drives the distributor, oil pump and fuel pump.

The cylinder head is of crossflow design with the inlet manifold mounted on the lefthand side and the exhaust manifold mounted on the right-hand side.

Lubrication is by means of a bi-rotor pump which draws oil through a strainer located inside the sump, and forces it through a fullflow filter into the engine oil galleries where it is distributed to the crankshaft, camshaft and auxiliary shaft. The big-end bearings are supplied with oil via internal drillings in the crankshaft. The undersides of the pistons are supplied with oil from drillings in the big-ends.

The distributor shaft is intermittently supplied with oil from the drilled auxiliary shaft. The camshaft followers are supplied with oil via a drilled spray tube from the centre camshaft bearing.

A semi-closed crankcase ventilation system is employed whereby piston blow-by gases are drawn into the inlet manifold via an oil separator and control valve.

Engine oil and filter - renewal

Refer to Chapter 1, Section 8.

Valve clearances - checking and adjustment

Refer to Chapter 1, Section 23.

Crankcase ventilation system - inspection and maintenance

Refer to Chapter 1, Section 35.

See also:

Weber 2V carburettor - adjustment
Idle speed and mixture adjustment 1 Refer to Chapter 1. Fast idle speed (XR3 models) 2 Remove the air cleaner as described in Section 2. 3 Have the engine at normal operating temperature, with ...

Auxiliary drivebelt check (Every 12 000 miles (20 000 km) or 12 months)
1 Refer to the Specifications at the beginning of this Chapter and check the tension of each drivebelt at the point stated. Check the full length of each drivebelt for cracks and deterioration. It ...

Hydraulic system - bleeding (conventional braking system)
Note: On cars equipped with the Anti-lock Braking System, refer to Section 23. Warning: Hydraulic fluid is poisonous; wash off immediately and thoroughly in the case of skin contact, and seek imm ...

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