Start by drawing a rectangle for the engine block. The width of the rectangle should be about twice the height.

Inside the engine block, draw four circles for the pistons. The pistons should be evenly spaced and should be slightly smaller than the engine block.

Next, draw four lines connecting the pistons to the crankshaft. The crankshaft should be drawn at the bottom of the engine block.

At the top of the engine block, draw a line for the camshaft. The camshaft should be parallel to the crankshaft.

Next, draw eight small circles for the valves. The valves should be evenly spaced and should be located above the pistons.

Draw a curved line for the intake manifold. The intake manifold should start at the bottom of the engine block and end at the top of the engine block.

Draw a similar curved line for the exhaust manifold. The exhaust manifold should start at the top of the engine block and end at the bottom of the engine block.

Draw a rectangle at the bottom of the engine block to represent the oil pan. The oil pan should be about the same width as the engine block, but it should be taller.

Add any necessary accessories, such as the water pump, alternator, and power steering pump.

Once you have the basic outline of the engine, you can start to add details. Add lines to represent the ridges on the pistons, the grooves on the camshaft, and the bolts on the engine block.

Once you are satisfied with the details, you can ink the drawing with a pen or marker.