Engine Parts Piston Movement… The piston moves & , but we need motion to make the wheels spin Changing reciprocating motion to rotary motion is the job of the connecting rod and crankshaft…
Opening the Valves A Camshaft is needed to push the valves open… As the camshaft spins, the lobes push the valves open
How the camshaft turns… The camshaft is mechanically connected to the crankshaft with either a… Timing chain Timing belt Timing gears
Camshaft Locations… Camshafts can be located right in the engine block, or overhead on top of the valves…
Pros & Cons of OHC vs cam-in-block outdated technology (but still widely used) more moving parts valve movement is less precise noisier
Pros & Cons of OHC vs cam-in-block OHC, DOHC: more precise valve action becoming widely used
Closing the Valves A valve spring closes the valve tightly against the valve seat…
Preventing pressure loss… Pressure loss past the valves is prevented by the valve spring closing the valve tightly against the valve seat…
Controlling leakage past the piston… Compression rings are needed to prevent burning gases from leaking past the piston into the crankcase…
Oil Control Rings Excessive amounts of oil are wiped off the cylinder walls by oil control rings…
Engine Block & Cylinder Head Materials Two metals used in engine blocks and cylinder heads are… Cast iron ~ heavy ~ inexpensive ~ painted Aluminum ~ lighter ~ $$$ ~ unpainted ~ warps easily when overheated