Compression Systems & Internal Combustion Theory

Most valve seats used on 4-stroke engines have a 45-degree angle.

• True

• False

The piston rings rotate around the ring grooves during operation due to harmonics.

• True

• False

The pressure on the piston, the size of the piston, and the length of the connecting rod determines the amount of torque produced during the power stoke.

• True

• False

A horsepower figure can be calculated direclty from the engine displacement in modern engines.

• True

• False

An engine with a longer stroke produces more torque than an engine with a shorter stroke that has the same displacement.

• True

• False

Torque is a twisting force that tends to cause rotation.

• True

• False

Most pistons are eliptical to

• match the taper of the cylinder

• wedge the fuel and air mixture

• leave room for carbon build-up at top

• allow for heat expansion and grow perfectly round

The piston and ring assembly should be installed into the cylinder

• after spring with penetrating oil

• dry to ensure rapid break-in

• with a ring compressor

• after coating with bearing grease

Small engine pistons must withstand ______________

• mechanical load

• thermal stress

• pressure fluctuations

• all of the above

Camshaft timing can be verified externally by using which of these methods?

• Valve overlap occurs exactly at TDC beween intake and exhaust strokes

• You have to pull the side cover or sump and verify dot to dot

• Valve overlap occurs exactly 1/2” before TDC on the exhaust stoke

• Not possible