AG Mechanics CDE Practice Exam

Valves have a direct effect on:

1. air intake

2. engine block temperature

3. compression

4. piston speed

The correct answer is: air intake

Valves have a direct effect on air intake in an engine. The valves control the intake and exhaust of air, fuel, and exhaust gases within the combustion chamber. By opening and closing at specific times, the valves regulate the flow of these elements into and out of the cylinder, which directly impacts the engine's performance and efficiency. This process is crucial for proper combustion and power generation in the engine. The other options are not directly affected by valves in the same way as air intake. While engine block temperature, compression, and piston speed can be indirectly influenced by the operation of the valves, their direct impact lies in controlling the air intake process.