General Engine Construction

GENERAL DESCRIPTION
The 4.3L engine is a 90-degree V6 type, overhead valve, liquid cooled engine, The 4.3L engine has a cast iron block and heads.

The crankshaft is supported by four precision insert main bearings, with crankshaft thrust taken at the number four (rear) bearing. The bearings are retained by bearing caps that ate machined with the block for proper alignment and clearances. The connecting rods are forged steel, with precision insert type crankshaft bearings. The piston pins are a press fit in the connecting rods. The pistons are cast aluminum alloy. The piston pons use a floating fit in the piston.

The camshaft is supported by four plain type bearings and is chain driven. Motion from the camshaft is transmitted to the valves by valve lifters (roller type), pushrods and ball type valve rocker arms. The valve rocker arms are retained on individual threaded-in studs. The valve guides are integral within the cylinder heads.

The 4.3L engine uses a cast iron balance shaft mounted in the crankcase above and in line with the camshaft. A camshaft gear drives the gear attached to the balance shaft. The front end of the balance shaft is supported by a ball bearing and the opposite end uses a sleeve bearing.

A two-piece Central Sequential Multiport injection (SFI) manifold assembly is used. The (SFI) manifold consists of an upper composite and lower cast aluminum manifold. The lower manifold has an exhaust gas recirculation (EGR) port cast into it for the mixture of exhaust gases with the fuel air mixture.

The intake manifold also houses the Central Sequential Multiport injection (SFI) system. The delivery tubes independently distribute fuel to each cylinder through nozzles located at the port entrance of each manifold runner where the fuel is atomized.