foreigneRS

PART A - Engine, Engine Management and Turbocharger

1.1 Engine Components

[b]The Cylinder Head[b]

The Cosworth light-alloy cylinder head has two overhead camshafts - one for the inlet side and one for the exhaust side.

A better volumetric efficiency is achieved by two inlet and two exhaust valves for each cylinder.

The valves are inclined and their "V" arrangement has an angle of 22,5°.

Valve stem diameter - inlet valve 7.0 mm
- exhaust valve 8.0 mm

The exhaust valve stems are sodium filled for optimum cooling.

The exhaust valve stem is stepped and its upper end is 7.0 mm to enable identical valve retainers and collets to be used.

The valves are actuated directly via hydraulic valve tappets. This eliminates the need for valve gap adjustment in service.

Valve seats and guides are fitted in production by shrinking. Replacement can be done by specialists for this type of work.

Valve guides - inlet: Copper-alloy inner dia. 7.0 mm
exhaust : Copper-alloy inner dia. 8.0 mm

1 = Camshaft - outlet side
2 = Camshaft - inlet side
3 = Hydraulic valve tappets
4 = Exhaust valves - sodium filled
5 = Valve stem seals
6 = Inlet valves
7 = Valve guides
8 = Valve seats

The valve stem seals have a press fit on the valve guides. Removal is done with special pliers, for installation a special installer tool is required (refer section "Cylinder head - remove and install").

Each camshaft is supported in five bearings with bolt-on bearing caps.

The cam bearings are machined in such a manner, that bearing liners are not required.

The bearing caps are marked 1 to 5 on the exhaust side and 6 to 10 on the inlet side with the counting starting from the front on both sides.

The front end of each camshaft is supported in a ball bearing to reduce the high start up torque transmitted through the timing belt of the sprocket wheel.

Camshaft support bearing
1 = Bearing cap
2 = Bearing retainer with bearing

Camshaft front bearing
1 = Camshaft sprocket wheel
2 = Bearing cap
3 = O-Ring
4 = Bearing retainer
5 = Ball bearing
6 = Camshaft
7 = Oil seal race
8 = Oil seal

The camshaft for the exhaust valves does not need this oil groove because of the position of the oil feed bore.

The oil feed bores are located on the side of the support bearings.

The camshaft for the inlet valves has bearing journals with oil grooves to ensure complete lubrication of the bearing surface.

Lubrication of the camshaft
1 = Oil supply bore
2 = Lubrication groove

The hydraulic valve tappets (bucket type) are supplied as an assembly. They should not be disassembled and must always be fitted into their original location.

Hydraulic valve tappets

1 = Camshaft
2 = Hydraulic valve tappets
3 = Valve stem
4 = Piston, cylinder and spring of the hydraulic valve tappet
5 = Tappet housing with oil chamber

The oil gallery of the cylinder head is fitted with a non-return valve which eliminates oil drain back after the engine is switched off
When starting the engine the anti-drain back valve opens for immediate lubrication of the camshaft journals and hydraulic tappets.

Anti-drain back valve in cylinder head
1 = Ball in closed position (engine switched off)
2 = Cross drilling
3 = Cylinder head bolt drilling (oil gallery)
4 = Main oil gallery

Anti-drain back valve in cylinder head
1 = Ball in open position (with engine in operation)
2 = Direction of oil flow

The cylinder head gasket differs from the standard OHC gasket in that it has revised openings to match the Cosworth cylinder head.

Components fitted to the Cylinder Head

Inlet side:
Inlet manifold (1)
Air chamber (2) with bolted on fuel rail (3), pressure regulator (4) and push fit fuel injectors (5).
Throttle housing (6) and elbow (7) .

The elbow is supported by a bracket (8) from the engine mounting. The elbow is fastened to the bracket by three pairs of special dished washers (9). This flexible mounting eliminates vibrations from the engine, which could affect the throttle position sensor. When disassembling, the position of the dished washers should be noted to ensure correct reassembling.

Outlet side: Two piece exhaust manifold (1) consisting of the primary manifold and the secondary manifold. Because of the high exhaust temperature, the manifold material consists of a heat* resistant cast iron (Ni-resist) .

The turbocharger is water-cooled and bolted to the exhaust manifold.