Exam 9: Camshafts, Lifters, Timing Belts, and Chains

Technician ​A says that excessive hydraulic lifter pump-up can occur if the valves float. Technician B says that hydraulic lifter valve adjustment on most engines positions the plunger at its center of travel in the lifter body. Who is right?

Technician ​A says that valve lifters are sometimes called "tappets." Technician B says that hydraulic lifters should leak very slowly between the plunger and the lifter body. Who is right?

Before using a chain wrench to hold a pulley in order to torque the crank bolt, what should you do?

Technician A says that a gear on the camshaft drives the distributor. Technician B says the exhaust and intake valves each operate on a separate lobe on the camshaft. Who is correct?

How many camshafts does a DOHC V6 have?

On pushrod flat tappet engines, why is the cam lobe tapered and the lifter off-center?

Camshafts are being discussed. Technician A says cam journals rarely wear so they do not need to be reground. Technician B says reground cams are more expensive. Who is correct?

Technician A says on a pushrod engine, the lifters do not need to be replaced when the camshaft is replaced. Technician B says when replacing a roller camshaft, the lifters must be replaced. Who is correct?

What is the term for the pushrod engine hydraulic lifter adjustment accomplished simply by torquing the adjusting nut against a shoulder?

Two technicians are discussing flat tappet camshafts. Technician A says that a valve lifter must be perfectly centered above its corresponding cam lobe. Technician B says a pushrod engine cam lobe is slightly tapered across its face. Who is right?

When there is a spiral gear on the camshaft of a pushrod engine, what is its purpose?

The exhaust valves shown in the preceding photograph are from a four cylinder interference engine that has failed. All of the valves are bent an equal amount. Which of the following could be the cause?

With regard to gear drives, what is backlash?

List two other names for valve lifter.

The cam lobes in the photograph shown here are for the number one cylinder and its companion on an in-line pushrod engine that rotates counterclockwise when viewed from the rear. The lobes are positioned:

The camshaft is the determining factor in how efficiently the engine pumps air.

Two factors of cam lobe profile are called lift and length.

When a worn lifter face contacts the outside edge of a flat tappet cam lobe causing severe wear, this is called edge _____.

To drive the oil pump and distributor, some overhead cam (OHC) engines use an extra shaft called a(n) _____ shaft that is driven by the crankshaft using an extra sprocket.

Technician A says on most pushrod engines, lifters have a concave face. Technician B says pushrods are stationary when the engine is running. Who is correct?