1. 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…

2. Opening the Valves A Camshaft is needed to push the valves open…
As the camshaft spins, the lobes push the valves open

3. How the camshaft turns…
The camshaft is mechanically connected to the crankshaft with either a…
Timing chain
Timing belt
Timing gears

4. Camshaft Locations…
Camshafts can be located right in the engine block, or overhead on top of the valves…

5. Pros & Cons of OHC vs cam-in-block
outdated technology (but still widely used)
more moving parts
valve movement is less precise
noisier

6. Pros & Cons of OHC vs cam-in-block
OHC, DOHC:
more precise valve action
becoming widely used

7. Closing the Valves
A valve spring closes the valve tightly against the valve seat…

8. Preventing pressure loss…
Pressure loss past the valves is prevented by the valve spring closing the valve tightly against the valve seat…

9. Controlling leakage past the piston…
Compression rings are needed to prevent burning gases from leaking past the piston into the crankcase…

10. Oil Control Rings
Excessive amounts of oil are wiped off the cylinder walls by oil control rings…

11. 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