A Boeing 747 is typically powered by four high-bypass turbofan engines, which are among the largest and most powerful in commercial aviation. The specific weight of a 747's engine depends on the variant; however, a General Electric CF6-80C2B1F engine, commonly used on the 747, weighs approximately 9,480 pounds (4,300 kilograms) without fluids. This substantial weight is a reflection of the engine's intricate design and the need for durability and high performance over tens of thousands of flight hours. Advanced materials and engineering techniques are employed to balance this mass with the requirements for fuel efficiency and thrust, highlighting the sophisticated nature of modern aerospace engineering. The weight of a 747 engine underscores the complexity and the technological marvel of commercial air travel.

A propane engine works very similarly to a gasoline engine but it uses propane as its fuel source instead of gasoline. Here's a simplified explanation: 1. Propane Fuel Supply: The engine is attached to a propane tank which serves as its fuel supply. This tank needs to be periodically refilled. 2. Fuel Conversion: The propane fuel is in a liquid state inside the tank. However, since an engine needs vapor to run, the propane system has a regulator that converts the liquid propane into a gas. 3. Combustion Process: When the engine is started, the propane gas is mixed with air and drawn into the engine's cylinders. 4. Power Generation: A spark plug ignites this mixture, causing a small explosion, or combustion, that pushes a piston down and turns the crankshaft to create power. 5. Exhaust: The LP-Gas (Liquid Petroleum Gas) is then exhausted, similar to exhaust gas in a gasoline engine. 6. Power Transmission: This power is then transmitted through the drivetrain to the wheels, making the vehicle move. 7. Repeat: This process is repeated in rapid succession, giving the engine the power it needs to run a vehicle. One advantage of propane is that it burns cleaner than gasoline, producing less harmful emissions. However, it is less energy-dense than gasoline, meaning you get less power from the same volume of propane as you would from gasoline.

Repairing or setting up engine timing requires technical knowledge about engines. If the engine timing is not correct, this might cause your vehicle's performance to decrease dramatically. Here is a general procedure: Materials: - Service manual - Timing light - Wrench Procedure: 1. Consult your vehicle's service manual to understand the type of engine timing your vehicle uses. Depending on your vehicle, it may utilize a distributor, a timing chain/belt, or it may have a distributor-less system that you need to be adjusted electronically. 2. Warm up the engine. The engine needs to be warm to ensure correct timing adjustment. Run your car for approximately 10 minutes in order for the engine to reach its normal operating temperature. 3. Locate and attach the timing light. Check your service manual to see where the ignition timing is located. Typically, the marks are on the harmonic balancer located on the crankshaft. The timing light needs to be clamped onto the number one spark plug wire and the power and ground leads attached to the correct battery terminals. 4. Check the timing. With the engine still running, aimed the timing light at the timing marks. Compare the measurement on the timing tab to the specification in your manual. 5. Adjust the timing if necessary. If the timing is not correct, loosen the distributor clamp bolt enough to allow slight rotation. Rotate the distributor until the right timing mark is hit, then tighten everything back down. 6. If you have a newer car with electronic timing, it will need to be adjusted by a mechanic unless you own the specific diagnostic and programming tools required for your car. 7. Once you are done, remove the timing light, replacement of any disconnected wires or moved parts, and shut down the engine. Remember, the procedure can vary largely depending on the vehicle make and model. Always refer to the service manual for best results. If you are unsure how to do it, it's better to take your vehicle to a professional mechanic who will do this for you. Disclaimer: Working on a vehicle engine can lead to severe injuries or damages if not done properly. It is recommended to hire a professional if you are inexperienced.