What is the clearance on the Trimmer Candle Bt 56

Despite the simplicity of the structure of the spark plugs, you need to work and handle them correctly. They need to be cleaned correctly, correctly selected and changed. However, even new options can sometimes cause problems. the machine can run unevenly, sometimes there are jerks (jerks) when picking up speed, as well as light knocking. Many immediately start looking for a cause in the ignition system. of course, after all, the candles are new! However, the gap between the electrodes may be to blame, it is enough to correct it and the engine will simply “sing”.

What is the clearance on the Trimmer Candle Bt 56


To get started, a small definition.

Spark plug clearance. this is the distance between the upper and lower electrodes, it is necessary for optimal operation and ignition of the fuel mixture. If this distance differs from the recommended norms, the engine will not work smoothly, either twitching or detonation similar to the “tripling” of your unit are possible.

In simple words, if the gap is different from the norm, set so from the factory or the seller, then you can shovel at least half of the motor, but you can not find the reason. It is especially pronounced on carburetor systems. BUT to start, I propose to start with the device and the principle of operation.

How cylinder ignition works

If we talk about candles, then this is like the last link in the ignition system, which is in direct contact with the air-fuel mixture. It is this element that sets it on fire, and does it either. efficiently and as laid down in the technical regulations, or ineffective for a number of reasons (by the way, wear is often the fault).

After the fuel mixture (gasoline and air) was fed into the cylinders, the piston starts to go up and compress it, thereby pumping pressure.

At peak or as it is commonly called at the “upper point”, the ECU gives an order and this structure ignites. over, his spark plug ignites. a spark runs between the electrodes, which is the catalyst.

However, ignition may not occur, I am not taking options with a malfunction of the ignition system now, I just set it to the wrong clearance. Thus, “transmission” may occur (that is, not ignition of the fuel mixture), which will cause your engine to work with low efficiency, and sometimes it will not start at all (for example, in the morning in winter). But why is this happening.

The effect of proper clearance on motor performance

Clearance is a really important parameter. It can be either large or too small.

Small clearance

If small values ​​are set between the electrodes, they will exhibit gaps in the ignition system. The thing is that the spark that forms between the electrodes that are as close as possible to each other is not enough to ignite the fuel mixture. The spark, although strong, is insufficient. That is why many cars when moving will actually twitch and not develop sufficient speed. On carburetors it can fill candles, which will only give problems. it will generally be troit. The clearance needs to be increased!

Small clearance is how much? If we talk about the size, then this is from about 0.1 to 0.4 mm. Be sure to check the candles after the purchase, I will give sensible recommendations a little lower, but for now we’ll talk about a long distance.

Large clearance

You know, still many manufacturers set the normal distance between the electrodes in advance. But over time, it itself can increase.

The thing is the wear of the candle, which manifests itself with high mileage. this is natural. After all, the electrodes are made of metal, which, under the influence of temperature and constant electric discharges, begins to slowly burn out. The upper one, similar to the letter “G”, and the lower one suffer. The upper one becomes thin, instead of a rectangular shape, it begins to round, because the sides burn. The bottom just sags down.

Due to this distance, the spark that passes between the contacts weakens. And significantly! It may also not be enough to ignite the fuel.

Often, because of this, the lower contact insulator breaks through, the whole thing is that the spark tries to find the shortest path between the electrodes.

In winter, there is a high probability that the car simply does not start.

Another important aspect, deposits can often appear on remote electrodes as a deposit, a spark so “suffers” from a long distance, and there is also a plaque! She may not pass at all. Therefore, it is important after a certain mileage, with our fuel it can already be 15,000 km, unscrew the candles if necessary, change them or clean them.

Large distance. from 1.3 mm and above.

Normal clearance to focus on

We have very specific limits. The lower one is from 0.4 mm (and all that is lower), the upper one is from 1.3 mm (and all that is higher). So what is considered the normal size for your car.

You know, and there are differences, they are primarily associated with the ignition system of the car, you can conditionally divide it into three types:

1) For carburetor type, with distributor. normal clearance from 0.5 to 0.6 mm

2) For carburetor type, with electronic ignition. 0.7. 0.8 mm

Video: What is the clearance on the Trimmer Candle Bt 56

3) Injector. 1. 1.3 mm

Why such difference? you ask. The answer is simple. the matter is in the ignition system and the electrical circuit. The carburetor has the lowest voltage, so the spark will be weaker, and therefore the clearance should be less. But the injector has the strongest energy system, so here the gap is increased, the normal one is considered from 1 mm, and on many foreign cars it is 1.1 mm.

How to check and how to set it

The process is not as complicated as it seems at first glance. To get started, simply unscrew the spark plugs, then look at the damage, if there are none, then you can clean it first, then check the clearance.

The probes are similar to the metal curved letters “G”, with different sizes, we simply substitute them between the electrodes and determine the gap with an accuracy of 97%. If it is larger, for example, on the injector than 1.1 mm, then the contacts are brought closer to each other, you can simply tap the handle of a screwdriver. If it is too close, then we move it apart, again it checks with a probe.

Check out my clearance video.

Modern technologies

What I want to say in conclusion, many will think “come on,” why should I bother with any distance between the electrodes! The guys are very wrong thoughts.

Firstly, you can save on fuel, studies show up to 5. 7%

Secondly, smooth engine operation is the key to driving safety.

Third, the correct gap between the candles increases their life, there is no likelihood that the insulator will break through (with an increased distance).

It should be noted that some companies, on the contrary, increase the number of contacts (electrodes), strengthen coils and the ignition system, all in order to make the mixture ignite better.

Also now there are more modern technologies that I think will soon come to replace. such as plasma candles.

They don’t have any electrodes at all, and fuel ignites a plasma beam, which is formed from electricity. As they write, they have already tested and they are making tests, and they say that the efficiency of the fuel mixture is increasing, which is a little more power, a little more economy and environmental friendliness.

And that’s it for me, read our AUTOBlog, it will be interesting.

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At the moment, there are several types of internal combustion engines. gasoline and diesel. And if the mixture’s arson is not required for the operation of the latter (it burns from the compression force), then in the case of gasoline a spark is needed. It is produced by a special element. a candle. Those are available on injection and carburetor machines. During operation, motorists often wonder what kind of clearance should be on the candles. Today we will talk about this topic in more detail.

About the ignition

A candle is the last element that comes in contact with the fuel-air mixture. Its main function is to set fire to the fuel at the moment when the piston is at top dead center. Voltage is supplied from high voltage wires. In turn, the interval between the supply of a spark is set by the ignition coil. When the piston is at TDC, a spark runs between the spark electrodes. She is the catalyst for this process.

The mixture ignites, the compression energy is transmitted to the piston. After the removal of gases, the process is repeated again. However, in order for the spark to be able to pierce the electrodes normally and ignite the mixture, the gap should be optimal. During operation, it changes. So, distinguish between small and large gaps. How they affect the operation of the engine, we will describe further.

What is the effect of small clearance?

If the gap between the electrodes is small (less than 0.4 millimeters), this will primarily be manifested in the nature of the engine. In this case, the owner will observe misfire. Why is this happening? The fact is that a powerful spark is required to set fire to a combustible mixture. And since the distance between the electrodes is small, then its strength will be insignificant. As a result, the combustible mixture will ignite once. The motor starts to troit. On carburetor aggregates often “floods” candles. This is not very good, as the motor operates in overload mode.

Large clearance is not always good

Therefore, if the spark is weak with a small gap, it must be maximized. But it is not so. If the gap is 1.3 millimeters or more, the spark will simply not pass between the electrodes. The motor will start to troit again. In addition to this, a candle deposit will appear.

How often to check?

Note that the manufacturers themselves do not oblige to check and adjust the gap (including iridium candles). However, practice shows that over time this parameter automatically changes in one direction or another, since the candle is constantly under voltage and high pressure. What to do in this case? Experienced motorists recommend checking the clearance on spark plugs every 15 thousand kilometers and, if necessary, correcting the readings.

What is the norm?

So, we have certain data. Small clearance is everything below 0.4 millimeters. Large. 1.3 and above. What clearance should be on candles? It all depends on the type of food. On carburetor cars with a distributor ignition system, this parameter is 0.5-0.6 millimeters. But not all units should have such a clearance on the candles. The carburetor with electronic ignition works fine with a clearance of 0.7-0.8 millimeters.

Spark plug clearance for gas

How to set?

If you notice that the car began to behave differently, misfires appeared, it is worth checking the condition of the candles. They may have the wrong clearance. To adjust the parameter, disconnect the high-voltage wires and unscrew the candle with a special key (as in the photo below).

So, we pass to setup. Using probes, we determine the exact clearance on the spark plugs. Please note that on cars with a contact system (old Zhiguli and Muscovites) this parameter is 0.1 mm lower than on contactless ones. If the gap is less than normal, the electrode is bent with a flat screwdriver. If the value is higher, the element is pressed with the same tool, only on the other side. Some candles may have a lateral arrangement of the electrode (and there are several).

In this case, a gap is set for each element. Take-off should be minimal. Having set the gap of one candle, we twist it into place, put the armored wires and proceed to set up the next one. It is important not to confuse the location of the high voltage wires. Therefore, twist the candles one at a time, and not all at once. Or make special marks. Otherwise, the motor may simply not start. At this stage, the setting of the spark plugs can be considered complete.

Why is sticking so important?

A correctly adjusted candle is not only the key to the coordinated operation of the engine. The clearance parameter also affects fuel consumption. By setting the desired distance between the electrodes, you will reduce it by 5-6 percent. Also, the normal clearance positively affects the life of the candle itself, since it will no longer pierce the insulator.

If you regularly monitor this parameter, the life of the candle can reach 60 thousand kilometers. This applies to both injection and carburetor engines.


So, we found out what the clearance should be on the candles, and how to properly adjust it. As you can see, the procedure is very simple. Even a novice motorist can cope with it. In conclusion, we note that the gaps need to be checked on new candles (the central electrode may have been bent during transportation). That’s all. We hope this article helped you solve this issue.