Chapter 13 PowerPoint

Define these Technical Terms using the textbook:

1. camshaft lobe

2. camshaft duration

3. camshaft lift

4. valve guide

5. valve seat

6. valve keeper

7. valve seal

Answer these discussion questions using the textbook:

1. Explain the purpose of intake and exhaust manifolds.

Read the chapter summary below:

■ An engine top end basically includes the cylinder head, valve train, valve cover, and the intake and exhaust manifolds.

■ A bare cylinder head is a head with all its parts removed.

■ An integral valve guide is part of the cylinder head casting. A pressed-in valve guide is a separate sleeve forced into a hole machined in the head.

■ The valve seat angle is the angle formed by the face of the seat.

■ An interference angle is a 1/2° to 1° difference between the valve seat face angle and the angle of the valve face.

■ The valve face angle is the angle formed between the valve face and valve head.

■ An umbrella valve seal is shaped like a cup and can be made of neoprene rubber or plastic.

■ An O-ring valve seal is a small round seal that fits into an extra groove cut in the valve stem.

■ Spring tension refers to the stiffness of a valve spring.

■ A valve spring shim is a very thin and accurately machined washer used to increase spring tension.

■ Valve retainers and keepers lock the valve spring on the valve.

■ A valve rotator turns the valve to prevent carbon buildup and hot spots on the valve face.

■ With dual overhead cam engines, there are two camshafts — the intake camshaft and the exhaust camshaft. The intake camshaft operates all the intake valves in the cylinder head. The exhaust camshaft operates all the exhaust valves.

■ Camshaft lift is the amount of valve lift produced by the cam lobe.

■ Camshaft duration determines how long the valve stays open.

■ Valve timing refers to valve opening and closing in relation to the position of the pistons in the cylinders.

■ Valve overlap is the time when both of the intake and exhaust valves in the same cylinder are open.

■ Valve lifters, or tappets, ride on the camshaft lobes and transfer motion to the other parts of the valve train.

■ Pushrods are metal tubes with specially formed ends.

■ Rocker arms transfer valve train motion to the valve stem tips.