1. Why is there an exaust valve. Isnt it only a port. Where do the gases that go into the exaust valve go?2. How does air enter the intake valve. If you look at a push rod diagram, you cant see where the air is enteringCan someone explain to me the valve concept
You're not dumb for trying to learn. In a 4 stroke engine the air goes into the intake manifold and into the intake ports on the head. There it interacts with the valve, which when opened allows the air to be drawn into the cylinder. Then the engine goes through the power stroke and then the exhaust is forced out through the exhaust valve.
Hey mechanic wannabe, The intake valve opens, the piston moving downward pulls the fuel mixture into the combustion chamber, the fuel explodes under pressure caused by the piston rising and both valves remain closed. When the piston comes back up the exhaust valve opens and all the burnt fuel leaves the combustion chamber and goes down the exhaust pipes until blown out the end of the exhaust system.
The camshaft is turned by the crank shaft and is in time with it. the cam shaft either pushes the valves open and closed or pushes on lifters or pushrods that drive the rocker assemblies that move the valves. On a two cycle engine yes under most circumstances the exhaust valve is only a port. On a 4 cycle engine like on a vehicle it has exhaust and intake valves. When the piston is on the exhaust stroke the exhaust valve is pushed open, the piston comes up and pushes the exhaust gas out through the open valve, near the top of the piston stroke the intake valve begins to open as well and for a very brief moment both valves are open this is known as valve overlap. This allows incoming air to help expel the burnt exhaust gas. The exhaust gas goes out through the exhaust port through the exhaust piping and into the air. When an engine is running or cranking (pistons moving) it creates a natural vacuum which draws in air, when the intake valves open air is drawn into the combustion chamber pretty simple. Then the air is mixed with fuel vapor and when the piston comes up on the compression stroke the spark plug fires and the air fuel mix burns and drives the piston down. The valves allow the engine (AKA some call it an air pump) to work and pump air. Without them the pistons would do nothing absolutely nothing.
