john daniel 4843

What is taper and ovality in the bore, how is it caused how do you check it?

Taper and ovality are used to describe the conditions of the cylinder bore.
Ovality is the difference between a and b
Taper is the difference between the large diameter at the first measurement and the smallest diameter at the 3rd measurement.

to check the taper you need to take a measurement at the top of the cylinder 90 degrees from the wristpin direction, then one at the bottom of the piston travel in the cylinder. then subtract the smaller number from the larger and you've got your Out of round measurement.

Ovality on the other hand requires a minimum of 4 measurements. One across the top of the cylinder parallel to the wrist pin direction(when installed), then one at the top perpendicular to the wrist pin direction(when installed), then repeat for the lower section of the cylinder. Take the larger number and subtract the smaller number and you have your "out of round" measurement on ovality. Repeat for the lower section. It's more common practice to do 6 measurements top, center, lower
 

john daniel 4843

What is the bore and stroke.

Bore - The size of the inside diameter (I.D.) of any machined hole. Typically this refers to the I.D. of the cylinders.

Stroke - The amount that the crankshaft moves the pistons within their bores from the bottom to the top. 69mm is stock for all 1500/1600 bases engines.

john daniel 4843

What is the purpose of the crankshaft,camshaft,valves collects(keepers),valve stem seals,head gasket,pistons,piston rings name them all, cam belt,flywheel?

Crankshaft - This is the heart of the engine. This is what spins and provides the motion for all the other parts in the engine con-rods, pistons, transmission, etc. All other parts in the engine work toward getting the crankshaft to turn fast and powerful.

Camshaft - A part of the short block, the cam is responsible for timing the opening and closing of the valves as well as determining how far they open up.

Keeper - These are little tapered half-round parts which lock onto the valve stem by the grooves. The outer diameter of the keeper is tapered. This in turn locks into the retainer which holds the valve spring in place.

Piston - The part which compresses the combustion fuel/air mixture in the cylinder on the compression stroke. Pistons come in 3 basic flavors; domed top (high CR), flat top (standard CR) and dished top (low CR).

Piston Rings - These provide a good seal between the piston and the cylinders wall. There are 2 top rings, or compression rings. The bottom ring is actually in 3 pieces (2 rings and a spacer). This is your oil control ring.


Head Gasket - A round copper ring that fits between the tops of the cylinders and the heads.

Flywheel - The large, heavy round plate which is held on the front of the engine with the gland nut. This is part of what couples the transmission to the engine. The clutch pressure plate mounts to the flywheel. The gear teeth on the outer edge are what the starter engages to start the engine.

john daniel 4843

Who and what year was the four stroke engine invented.

In May 1876, Nicolaus Otto built the first practical four-stroke piston cycle internal combustion engine. He continued to develop his four-stroke engine after 1876 and he considered his work finished after his invention of the first magneto ignition system for low voltage ignition in 1884. Otto's patent
was overturned in 1886 in favor of the patent granted to Alphonse Beau de Roaches for his four-stroke engine. However, Otto built a working engine while Roaches' design stayed on paper. On October 23, 1877, another patent for a gas-motor engine was issued to Nicolaus Otto, and Francis and William Crossley. 

Nicolaus Otto invented the gas motor engine. An engineer and experimenter, Nicolaus Otto invented the first practical alternative to the steam engine in 1876 -- the first four-stroke internal combustion engine. He called it the "Otto Cycle Engine."

john daniel 4843 engines

How does a four stroke engine work? Name the cycles ,I want to now what the piston is doing and the valves on each stroke.

Intake stroke: The intake stroke, or induction stroke, is the first stroke in a four-stroke internal combustion engine cycle. It involves the downward movement of the piston, creating a partial vacuum that draws a fuel/air mixture into the combustion chamber.

Compression stroke: The compression stroke is the second of four stages in an otto cycle or diesel cycle internal combustion engine. In this stage, the mixture (in the case of an Otto engine) or air (in the case of a Diesel engine) is compressed to the top of the cylinder by the piston until it is either ignited by a spark plug in an Otto engine or, in the case of a Diesel engine, reaches the point at which the fuel which has been injected spontaneously combusts, forcing the piston back down.

Power stroke: A power stroke is, in general, the stroke of a cyclic motor which generates force.


Exhaust stroke: The exhaust stroke is the fourth of four stages in an internal combustion engine cycle. In this stage gases remaining in the cylinder from the fuel ignited during the compression step are removed from the cylinder through an exhaust valve at the top of the cylinder. The gases are forced up to the top of the cylinder as the piston rises and are pushed through the opening which then closes to allow fresh air/fuel mixture into the cylinder so the process can repeat itself.

The work of piston in each stroke
The cycle begins at top dead center (TDC), when the piston is furthest away from the crankshaft. On the first stroke (intake/induction) of the piston, as the piston descends it reduces the pressure in the cylinder, a mixture of fuel and air is forced, by at least atmospheric pressure, into the cylinder through the intake port. The intake valve (or valves) then closes and the following stroke (compression) compresses the fuel-air mixture.The air-fuel mixture is then ignited, usually by a spark plug for a gasoline or by the heat and pressure of compression for a Diesel cycle or compression ignition engine, at approximately the top of the compression stroke. The resulting expansion of burning gases pushes the piston downward for the third stroke (power) and in the fourth stroke (exhaust) the piston pushes the products of combustion from the cylinder through an exhaust valves.

4843 engines john daniel

components used in petrol engines

Energy produced by fuel produces reciprocating motion of piston.
This reciprocating motion is converted to rotary motion of crank using slider-crank mechanism.
Crank is connected to flywheel, whose basic purpose is to provide constant angular velocity using gyroscopic motion.
Flywheel is connected to gearbox via clutch.
Gearbox transmits the rotary motion of flywheel to the tyres.The rotary motion of crank is coordinated with that of cam-shaft via gear mesh.
Thus, rotations of perfectly aligned cams are responsible for opening and closing of inlet and exhaust valves of combustion chamber.
Air and tiny droplets of petrol are mixed in a device called Carburetor. Its flow to cylinder is controlled by a throttle.

Starter is used to provide initial torque for rotating the flywheel , required to start the engine.
Starter Motor is fed with current from battery. Petrol Engine requires a motor of around 60rpm. Shaft of this motor engages with the toothed rim of flywheel.

The rotation of flywheel rotates the crank, which leads to descending motion of piston.

Rotation of crank leads to rotary motion of cam. Cam-Shaft mechanism leads to opening of inlet valve.

1st STROKE (INDUCTION STROKE) - Descending motion of piston leads to production of suction pressure which sucks air and fuel mixture to the combustion chamber from carburetor via inlet valve.

Inlet Valve closes.

2nd STROKE (COMPRESSION STROKE) - Flywheel still rotating with the help of starter motor produces ascending motion of piston.

Pressure and Temperature of fluids increases. Droplets of Petrol vapourise. This facilitates easy ignition.

Ignition Coil (Condenser) is an induction coil that steps up 12V from battery to 12KV needed to produce spark in Spark Plug.

The electrical network from Ignition Coil passes to Distributor. A point to note as of now, there are multiple combustion chambers in an engine. Each of them requires independent ignition. The role of distributor is to distribute the current from Ignition Coil to Spark Plug in each cylinder.

Spark Plug produces a spark which initiates combustion inside the combustion chamber.

Starter Motor disengages with the flywheel.

Combustion of fuel produces immense energy. This leads to expansion of gases produced during combustion.

3rd STROKE (POWER STROKE) - Expansion of gases pushes the piston downwards. This is the only stroke where work is produced. In other 3 strokes, flywheel provides necessary energy to rotate the crank.

A part of work done during this stroke is stored in flywheel in the form of magnetic energy. Remaining work is transmitted to crank.

Again, perfectly timed rotation of cam-shaft leads to opening of Exhaust Valve.

4th STROKE (EXHAUST STROKE) - Again, Energy stored in flywheel during Power Stroke is utilized to rotate the crank in this stroke. This produces Ascending motion of piston.

Since, exhaust valve is open, all the gases escape through this outlet.

Exhaust Valve closes.

the flywheel in 1st Stroke & 2nd Stroke is now powered by energy stored during Power Stroke of previous cycle (which, in 1st cycle was powered by starter motor).

4843 engines john daniel

describe the operating principles of diesel engines

The Direct Injection Engine
The engine uses the heat caused by compressing air in a cylinder, with a piston, to ignite fuel oil which is injected into the cylinder. This oil burns and creates an increase in pressure which forces the piston back down the cylinder, providing the power. The burnt gasses are exhausted from the cylinder and replaced by fresh charge through valves, commonly positioned above the piston in the cylinder head.
The fuel oil is pushed into the engine under high pressure at the correct time by an injector pump. The oil is sprayed into the engine cylinder as a very fine mist from the nozzle of an injector. The fine fuel oil mist readily mixes with hot air in the cylinder, ignites and provides an efficient burn. The injector pump also meters the amount of fuel delivered. The more fuel the more power the engine.

 Operating cycle of the common four stroke engine .the engine provides one combustion event during the four piston strokes

Its a DI cylinder.

fuel being injected into a swirl chamber with a heated glow plug

 

4843 engines

describe the operating principles of petrol engines

A model of a four stroke petrol engine.

• Rocker (A)
• Inlet Valve (B)
• Piston (C)
• Connecting Rod (D)
• Crankshaft (E)
• Camshaft (F)
• Pushrod (G)
• Exhaust Valve (H)

The 4 stroke is so called as all the required functions to make the engine run are completed in 4 strokes of the piston-- inlet, compression, power, exhaust.

The first stroke is the inlet or induction stroke. As the piston moves down inside the cylinder, the inlet valve opens allowing a fresh change of mixed gasoline and air to enter the cylinder.

After the piston has completed the inlet stroke, the inlet valve closes and the piston returns back up inside the cylinder to compress the mixture in readiness for the power phase.

After the gases have been ignited, the piston is driven down inside the cylinder forcing the crankshaft to rotate.

As the piston completes its power stroke, the exhaust valve opens in readiness for the exhaust phase.