The cam acts directly on a rocker in which type of engine?

The cam acts directly on a rocker in which type of engine?

• A. Pushrod Engine
• B. Overhead Valve Engine
• C. Cam-in-Block Engine
• D. Single Overhead Cam Engine & Dual Overhead Cam Engine

Answer: (D)

The motion that opens a valve comes from the camshaft, and whether that cam acts directly on a rocker depends on where the cam lives in the engine. In engines with the camshaft in the cylinder head (overhead cam designs), the cam lobes drive a follower that sits on or directly engages a rocker arm, so the cam can act on the rocker to open the valve. In contrast, engines with the cam in the block (pushrod or cam-in-block designs) place lifters, pushrods, and then the rocker between the cam and the valve, so the cam does not touch the rocker directly. Because overhead cam engines—both single and dual—allow direct cam-to-rocker interaction, the option that includes both Single Overhead Cam and Dual Overhead Cam engines is the best answer.

The motion that opens a valve comes from the camshaft, and whether that cam acts directly on a rocker depends on where the cam lives in the engine. In engines with the camshaft in the cylinder head (overhead cam designs), the cam lobes drive a follower that sits on or directly engages a rocker arm, so the cam can act on the rocker to open the valve. In contrast, engines with the cam in the block (pushrod or cam-in-block designs) place lifters, pushrods, and then the rocker between the cam and the valve, so the cam does not touch the rocker directly. Because overhead cam engines—both single and dual—allow direct cam-to-rocker interaction, the option that includes both Single Overhead Cam and Dual Overhead Cam engines is the best answer.