Q1. What material is commonly used to provide a wearing surface in a liquid-cooled engine for the pistons to ride against?

Q2. What are the two types of cylinder sleeves?

Q3. What are the two types of core hole plugs used in an internal combustion engine?

Q4. What is the basic foundation of all air-cooled engines?

Q5. A properly made exhaust manifold results in what type of action to help an engine get rid of exhaust gases?

Q6. In an exhaust-heated intake manifold, gases diverted to the manifold are controlled by what valve?

Q7. What two basic types of oil seals are currently being used on engines?

Q8. What ate the structural components of a piston?

Q9. What are the three types of piston pin configurations?

Q1O. What three functions do piston rings serve?

Q11. What part is the backbone of an internal combustion engine?

Q12. The valve actuating mechanism is made up of what engine parts?

Q13. What are the three basic shapes of a poppet-type valve?

Q14. What type of valve is preferred in a vehicle using unleaded fuel?

Q15. What are the two basic types of valve seals?

Q16. What three characteristics of a valve spring should you check?

ENGINE ADJUSTMENT AND TESTING

LEARNING OBJECTIVE: Describe The techniques used in adjusting engine valves. Recognize basic engine testing procedures and required tools.

Proper and uniform valve adjustments are required for a smooth running engine. Unless the clearance between the valve stems and rocker arms or valve lifters is adjusted according to the manufacturer's specifications, a valve does not open and close at the proper time, and engine performance is affected.

In most shops, the Navy provides accurate and dependable testing equipment. But having the testing equipment in the shop is NOT enough. The supervisor and crew must know how to use this equipment properly since it provides the quickest and surest means of determining what is wrong and where the fault lies.

VALVE ADJUSTMENT

Valve adjustment, also called tappet clearance adjustment or rocker adjustment, is critical to the performance and service life of an engine. If the valve train is too loose (too much clearance), it can cause valve train noise (tapping or clattering noise from the rocker striking the valve stems). This can increase part wear and cause part breakage. Valves that are adjusted too tight (inadequate clearance) may be held open or may not close completely. This can allow combustion heat to blow over and burn the valve.

When reassembling an engine after reconditioning the valves, make sure the adjusting screws are backed off before rotating the engine. A valve that is too tight could strike the piston and damage either the piston or the valve, or both. Adjust the valve according to manufacturer's specifications, following the recommended procedure.

On any engine, after valve adjustments have been made, be sure that the adjustment locks are tight and that the valve mechanism covers and gaskets are in place and fastened securely to prevent oil leaks.

Overhead Valves

Most overhead valves are adjusted "HOT"; that is, valve clearance recommendations are given for an engine at operating temperature. Before valve adjustments can be made properly, the engine must be run and brought up to normal operating temperature.

To adjust a valve, remove the valve cover and measure the clearance between the valve stem and the rocker arm. Loosen the locknut and turn the adjusting