Step-by-Step Instructions for Timing Setting Without a Timing Light
- Obtain a vacuum pressure, dwell time, and RPM in step 1 (revolutions per minute)
- Step 2: Loosen the bolt holding the distributor on the engine.
- Step 3: Slowly rotate the distributor.
- Step 4: Carburetor adjustment.
In This Article...
What occurs if the valve timing is off?
Valve timing is the first. A four-cycle engine requires pretty accurate timing for the valves to open and close in order to operate properly.
If the valve timing is off, the engine won’t start in a “freewheeling engine or a side-valve engine, both of which are normally quite low-performance engines. Correct timing is much more crucial in a “interference engine” since the valves and pistons share some space at various times. This style of motorcycle is the most common today. Not only will the engine not start if the valve timing is off, but it might also result in catastrophic damage if the piston collides with the valves. Typically, this leads to damaged pistons and bent valves.
This is the time that is being discussed when someone mentions their timing belt or chain. For significantly modified mills, high-performance engine builders will occasionally alter the valve timing, but for the most part, the timing should be set according to the manufacturer’s recommendations. Many riders choose to delegate associated tasks to a professional because the cost of screwing up valve timing, such as during a timing belt repair, is quite substantial (engine rebuild).
Ignition timing—does it impact idle?
Yes. Changing the timing will alter the idle speed at the same throttle setting in the case of both valve timing and distributer timing (in older automobiles with a spark distributer), as it will alter the engine’s efficiency at that throttle setting.
What occurs if the ignition timing is set too far forward?
The charge will burn during the compression stroke if the ignition time is set too far in advance, causing the engine’s pressure to peak during that phase. The piston is in opposition to moving toward TDC due to this peak pressure. As a result, there is a loss of power and a possibility of knocking.
The charge will burn during the compression stroke if the ignition time is set too far in advance, causing the engine’s pressure to peak during that phase. The piston is in opposition to moving toward TDC due to this peak pressure.
As a result, there is a loss of power and a possibility of knocking. Extreme instances might result in damage to the engine’s parts, such as the piston, connecting rod, crankshaft, etc.
The engine parts are overheated by the too advanced spark generation.
What timing should I use for my ignition?
The combination should fully burn at roughly 20 degrees ATDC, according to ideal conditions. The engine’s ability to produce power will be maximized in this way.
How do TDC and BTDC work?
The piston’s position in relation to top dead center is the parameter that determines when the spark plug will arc (TDC). The spark plug will therefore ignite when the crankshaft is 6 rotational degrees before the piston is at top dead center (TDC), if the timing standard is 6 degrees before TDC (BTDC) (BTDC).
How can I tell if my valves need to be adjusted?
Engine braking entails using techniques other than external brakes to slow down your car.
For instance, you can check the valve’s functionality by using throttle-braking, especially when descending from a steep drop and the accelerator pedal is stationary.
Oil will build up at the front of the valve cover over the head if a high intake manifold vacuum has already been produced and the engine is slanted downward. Additionally, when the accelerator is pressed after a lengthy coast, burned oil has a tendency to spew out of the tailpipe in considerable quantities.
What results from overly tight valves?
In overhead-cam engines, lobes on rotating camshafts directly open valves, while in overhead-valve (pushrod) engines, pushrods work on rocker arms to open the valves, which resemble spring-tensioned inverted golf tees. The distances between the lobes or rocker arms and the valve stems they act on may increase through time and use. This frequently results in clattering noises or increased engine vibrations, which a driver might not notice for a time because they build gradually, but which they will need to fix by adjusting. With exhaust valves, the clearance, sometimes referred to as the lash, between the valves and the valve train components can get smaller over time when the valves or valve seats deteriorate.
The air-fuel combination (or just air in certain modern engines) enters the cylinders by intake valves, which open and close, and exhaust valves allow exhaust gases to escape. As a result of the engine’s inability to “breathe naturally and run at full efficiency,” too much or too little valve clearance can produce poor performance or a rough idle. Too much space will probably cause the valves to clang and, over time, harm the valves, camshaft lobes, or rocker arms. The engine will lose power if there is insufficient valve clearance, which prevents the valves from closing completely and generates too much heat.
What occurs when timing is incorrect?
The ignition timing of an automobile is changed in accordance with any engine modifications. If not, your engine could have a number of issues with poor ignition timing, including banging, difficulty starting, increased fuel consumption, overheating, and decreased power.
Damage to the engine’s pistons or valves is a common internal cause of ignition timing errors. The timing of the ignition might be thrown off by an engine with a weak or loose timing belt that skips time.
What rpm determined beginning timing?
The advance can start at a lower rpm thanks to lighter springs. Heavy springs slow the rate of advance and postpone the start. Typically, a mechanical advance curve will begin to advance at 1,500 rpm and complete its advance at 2,600 rpm.
Does increasing the timing result in a hotter engine?
The temperature of the engine rises when ignition timing is advanced. More power is produced as you move closer to the MBT, but temperatures could rise to the point where melting is possible due to the combination of rising temperatures from compression and combustion. As a result of the heat-induced formation of the flamefront distant from the spark, which results in pressure spikes that might shock load components to failure, you might also wind up generating knock.
Pre-ignition, or when the engine “diesels,” can be caused by abnormally high temperatures. Only AFR can stop this; all spark timing adjustments fail to do so.
In fact, EGTs increase as ignition time is delayed because less fuel is burnt before exhaust starts to form. As the fuel contacts the catalytic converter or fresh air and burns on contact, low (rich) AFRs will also result in high EGTs.
Timing that is excessively advanced past MBT is never a desirable thing. If you don’t have knock, every degree of advancement will push you closer to the knock threshold as you lose power.
If you are not knock-limited, you should generally advance timing to MBT before reversing until you lose 3-5% torque. It will be just on the cusp of detectable loss, which lessens the likelihood that you’ll overachieve or begin knocking in warm weather.
But I’m only a casual tuner. I’m sure someone with actual expertise will join in and refute me.
Is the advance timing prior to or following TDC?
When the spark plug ignites during the compression stroke is controlled by ignition timing, also known as spark timing. Prior to top dead center, crankshaft rotation is used to measure ignition timing (BTDC).
- Spark plug starts to burn.
- The air/fuel mixture is ignited by the flame as it moves through the combustion chamber.
- Pressure inside the cylinder increases as the burning gases expand.
- When the piston reaches top dead center, the pressure is at its highest (TDC).
- The piston is pressed against the pressure as forcefully as possible, producing the most power.
However, the engine’s internal environment is always shifting. The speed of the flame varies with different cylinder head and piston configurations. In order to generate the highest pressure at the appropriate time, the spark must fire at various times. The answer is to move the timing forward or backward.
Ignition Advance
Timing advancement causes the plug to ignite earlier during the compression stroke (farther from TDC). Because the air/fuel mixture does not ignite quickly, preparation is necessary. The flame needs some time to ignite the entire combination.
An engine knock will occur if the timing is advanced too far, though. The amount of total advance needed will depend on the load and engine speed (rpm).
Ignition Retard
The plug fires later in the compression stroke when the timing is delayed (closer to TDC). Timing can be delayed to lessen detonation.
You will, however, lose power if the spark happens too late. This is the case with the Power Stroke since the cylinder pressure won’t reach its maximum until the piston is already on its way back down. Overheating and engine damage are further potential issues.
How is it controlled?
The microprocessor in most modern engines regulates the timing of the ignition. Timing can be managed in an engine with a distributor in a number of different ways. For more details, click on the links below.
Can timing affect how much fuel is used?
An engine’s ability to operate efficiently depends on the timing of the ignition. The fuel must be ignited at the right time during the combustion cycle for the engine to burn fuel properly. The fuel and air mixture won’t burn properly if the ignition timing drifts out of synchronization. Numerous symptoms that range in intensity and have an impact on everything from drivability to fuel economy can come from this.
Pinging/Knocking
Pre-ignition is occurring when there is pinging or knocking. When the piston has not finished its compression stroke and the fuel mixture in the engine cylinder is ignited too early, pre-ignition takes place. As the piston continues to try to compress the fuel and air mixture, this causes the fuel and air mixture to ignite and push back against it. Pre-ignition will result from timing that is too much in advance, which will ignite the fuel and air mixture too quickly.
Hard Starting
The right time must be used to ignite the gasoline and air combination inside the cylinders for an engine to start. It will be challenging to start the engine if the fuel-and-air mixture is not ignited at the proper time due to improper ignition timing, which causes the spark plugs to fire too early or too late.
Overheating
A fuel-and-air mixture will ignite too early in the combustion cycle if ignition timing is excessively advanced. This may result in an increase in the heat produced by combustion, which could overheat the engine.
Low Power
The spark plug will ignite the fuel-and-air mixture too late in the combustion cycle if the ignition timing is too far back. This leads to incomplete combustion of the fuel-and-air mixture and ignition occurring after the piston has already started to descend in its cylinder during the power stroke of the combustion cycle. An engine power loss is the eventual result.
Increased Fuel Consumption
Inaccurate timing will result in the fuel-and-air combination igniting in the cylinders at the incorrect moment. Engine power is decreased as a result of the fuel-and-air combination not being entirely burnt. The engine must burn more fuel to produce the same amount of power to move the car forward as a result of the inefficient combustion and reduced power, which increases fuel consumption and decreases fuel economy.