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The stand is designed for maintenance and repair of cylinder heads for passenger cars. To mount all cylinder heads on the stand, except for the head of the Moskvich car, the intake pipe and exhaust manifold studs are used. For attaching the head of the Moskvich car block, only the intake pipe studs are used.
A stand for repairing cylinder heads, drying out valves, removing crackers and removing valve springs on the stand, monitoring gaps in the sleeve-valve connection.
The cylinder head repair stand consists of three assemblies: a base, a rotary part and a slider with a bar. The latter are not shown in the figure. The base of the stand includes a stand and set screws.
Video (click to play).
We install the rotary part of the stand with trunnions in the grooves of the posts. We fix the rotary part in the required position with locking screws. The main and most difficult part of the turntable is the carrier plate. In the figure below, in order not to get confused in the holes and grooves, their markings are shown separately for each of the four cylinder heads.
When welding the pivot piece, pay attention to the location of the carrier plate. The easiest way to navigate is the 60 mm wide groove (see markings) for Moskvich cars. The side of the carrier plate shown in the second figure is not visible in the first figure.
Nuts are used to secure the cylinder heads to the carrier plate. In order to quickly find "your" holes in the carrier plate for each head, it is better to knock out or apply letters at the central holes. For example, if a VAZ Samara head is installed, then with the central pin you get into the hole with the letter "C", "M" - Moskvich, "B" - Volga, etc.
Drying valves, removing crackers and removing valve springs on a stand for repairing cylinder heads.
The slider with a rod is designed to dry out the valves or to remove the crackers and remove the valve springs. The slider moves along the guide. The bar can move in the slider. The bar is fixed in the slider with a locking screw. A swivel nut with a screw is installed at the end of the rod. The swivel nut is attached to the rod with a nut and an axle.
Locking the swivel nut in the desired position is carried out with a screw. By moving the slider along the guide bar in the slider and turning the nut, the screw is installed coaxially with the corresponding valve. Compression of valve springs and release of crackers is carried out with a screw through a desiccant.Hold the valve with your hand if necessary.
We make two rods - 300 and 405 mm long. The long rod is used only for drying the exhaust valves of the cylinder head of the UZAM engine. In all other cases, it is more convenient to work with a short barbell.
Usually, when the valves dry out, the spring support plates are separated from the crackers, as noted above, while holding the valve by hand. But there are also known cases when crackers were "welded" to plates. When drying the valves on the stand, in such cases, the valve springs are compressed and, placing a rag under the valve, they strike a sharp blow through the soft metal spacer in the center of the plate.
It is very difficult to measure clearance A in the sleeve-valve connection. But indirectly, by measuring the movement of the valve disc Dm, it is much easier. Calculation of the relationship between the clearance D and the displacement Dm (from the middle position of the valve to the extreme) will give the dependence
2.1. A complete movement from one extreme position to the other would be a double constraint.
With the maximum allowable clearance A equal to 0.15 mm, the movements in the bushing-valve connections must be within:
- VAZ cars: 0.022-0.055 mm.
You can measure the gaps on the cylinder head bench using a special tool. Its individual nodes are shown below.
If you make the base shown in the last figure, then the parts of the fixture can be used separately from the stand for repairing cylinder heads, like an indicator stand.
Based on materials from the book "Accessories for car repair". Ross Tweg.
High requirements for the accuracy of machining cylinder head elements in repair practice dictate the need to use specialized equipment.
Equipment for the repair of cylinder heads is produced by many companies, but not all samples of machine tools and tools are successfully used in practice. Our range of machine tools and tools consists only of the best models in their segment and meets all modern requirements.
When repairing the cylinder head (GVTs), cracks are welded and the plane is restored.
Surfacing, welding of cracks and chips. Mechanical damage to aluminum GVTs is eliminated by surfacing (shells) or welding (cracks and chips).
To restore the GVTs from aluminum alloys, electric arc surfacing with a tungsten electrode in an argon atmosphere is used. The source of thermal energy is an electric arc that burns between a non-consumable tungsten electrode and the workpiece. Argon serves as the shielding gas and wire as the filler material. Argon reliably protects molten metal from air oxidation. As a result, the weld metal is dense, without pores and cavities. The addition of 10.12% carbon dioxide and 2.3% oxygen to argon increases arc stability and improves weld metal formation. External protection of the argon jet by carbon dioxide allows to reduce the argon consumption by 3.4 times. Welding semiautomatic devices are most often used for surfacing under the conditions of a service station (Figure 7.11).
Rice. 7.11. Semiautomatic welding machine for argon arc welding and surfacing: a - scheme; b - general form; 1 - roller mechanism; 2 - filler material; 3 - cassette; 4 - electrode; 5 - mouthpiece; 6 - handle; 7 - argon; 8 - arc;
9 - welding current source; 10 - cylinder head
Arc 8 burns between a non-consumable (tungsten) electrode 4 and cylinder head 10. The arc is powered by a welding current source 9 through a conductive mouthpiece 5. The mouthpiece is electrically isolated from the burner body. The supply of argon 7 is carried out through the channel of the handle b, made of a dielectric material. A filler material (wire) is used to supply the weld pool with liquid metal 2. The filler material is fed into the arc by a roller mechanism /.
Restoration of the cylinder head plane. The planes of the cylinder head are restored by applying an additional layer of metal in places where cavities and cracks appear (by surfacing or spraying), followed by milling or grinding.
To apply an additional metal layer, STO most often use gas-dynamic spraying, which is implemented on Russian-made DIMED 405 and 412 installations (Fig. 7.12). Spraying technology includes heating compressed gas (air), feeding it into a supersonic nozzle and forming a supersonic air flow in this nozzle, feeding this powder material into this flow, accelerating this material in the nozzle by a supersonic air flow and directing it to the surface of the workpiece.
Milling of planes is carried out on vertical milling machines with a rotary table. A cast iron bed is installed on the base plate 5 3. Inside the bed are located
Rice. 7.12. Vertical milling machine:
/ - spindle; 2 - rotary faceplate; 3 - bed; 4 - jack; 5 - foundation slab; 6 - console; 7 - slide; 8 - table
Rice. 7.13. Layout of a surface grinding machine:
/ - stock; 2 - bed; 3 — table; 4 — vertical guides; 5 - column; 6 — grinding wheel; 7 - hydraulic cylinder
compartment for electrical equipment and gearbox. A rotary faceplate is installed in the upper part of the bed 2 with milling head and spindle 1. With a screw jack 4 the console moves along the vertical guides of the bed 6 with slide 7 (longitudinal, transverse and swivel) and table 8.
Grinding of planes is performed on surface grinding machines (Fig. 7.13). On the transverse guides of the bed 2 placed a vertical column 5. Along vertical guides 4 column moves grinding wheel head with grinding wheel 6. The circle is partially covered by a protective cover. The table moves along the horizontal guides of the bed 3. Longitudinal table movements are carried out by the rod 1 hydraulic cylinder 7. On the guides of the table can be installed: workpiece; machine vise, sinus vise, or magnetic plate.
1. What equipment is used to repair cylinder blocks?
2. What equipment is used for crankshaft remanufacturing?
3. What work is performed during the GBK repair and on what equipment?
Good afternoon. Starting this article, I will explain a little what will be discussed. It will be not only about special tools with which you can repair the cylinder head, but also about how to work with this tool correctly. It turns out that not everyone knows how to properly use a special tool and this sometimes leads to irreparable consequences. I will try to describe in detail the entire process of work so that you can independently do all the work on repairing the cylinder head.
So, let's begin. In principle, the whole process is practically the same, in the classics, in Samara and subsequent models. The first thing we have to deal with is the removal of the springs and valves (drying out of the valve). For this, a special puller is used.
Of course, there are many different devices, but this is the most pervasive. This is what we will consider. The puller is attached with the front part to the pin, and a special grip is installed on the spring plate.
Now we need a special substrate for the combustion chamber for the valve. Why is it needed? When you press the lever of the device, the valve will go down, and it will go through the appropriate path until it rests on its plate, for example, on the table on which you take the head. At this time, the spring will compress and prevent the crackers from being pulled out. This backing can be a piece of rubber of the right thickness or a block of wood.
Pressing on the lever, the valve rests against the substrate, and you can easily remove the crackers.
Put all the crackers neatly in a box, because then it is very difficult to look for the lost crackers.
There is, of course, a barbaric way of extracting rusks. It is worth resorting to it only in special cases when there is no special puller. This process is carried out with a hammer and a piece of metal pipe (a candle wrench works well here).
After striking, do not immediately remove the hammer, otherwise the crackers will fly apart. You can shove a piece of rags into the upper part of the tube, this will delay the flying out crackers.
The next tool we need is a valve guide puller. I wrote the process of replacing the valve guides in the article (Replacing the valve guides). There are different pullers. First (percussion).
Why shock? But because the pressing takes place by hitting the mandrel with a hammer. This method does not always go smoothly. There were cases when the mandrel went into a skew and removed a little metal from the bushing seating plane, thereby decreasing its seating density, which is not good in our case.
A widespread tool has become a screw smooth press-on puller.
This puller allows the bushing to be replaced smoothly and safely. They are sold in auto stores, but you can make it yourself, and I will definitely post it as I draw a drawing.
We also need a tool for removing and installing the valve oil seal. Care must be taken when removing and installing oil seals. Why careful? Because the side on which the oil seal is installed is very fragile and can be damaged.
For dismantling, special clamps are used, by the way, this clamp can be made by yourself. I saw a craftsman make a clamp from a sawn nut in half and welded to a round nose pliers.
The extraction method is simple. Cover the removable oil seal and rotate the grip strictly vertically along the axis in one direction and the other, while stretching upwards. It is strictly forbidden to loosen the oil seal to the sides, because there is a danger of damaging the side of the guide sleeve and the guide will need to be changed.
Installation of oil seals (caps) is done in a special mandrel.
Before installing the oil seals, check them for tightness. Try to put it on the rim of the sleeve with your hands. If it does not find it, then this is our oil seal and can be installed. If the oil seal is loose or loose, then it will leak oil and will not cope with its task.
Next, we need a tool such as a sweep.
I recommend using these reamers, because they have a guide for accurate entry into the hole. We need a reamer with a diameter of 8.00 mm. Deployment is as follows. Install the reamer into the just pressed-in guide sleeve and lightly press it until it comes out on the other side.
The next step will be lapping the valves. Before grinding the valves, they need to be processed with cones.
It is better to use such cutters. We need three cutters with different cutting angles. The first is 45 degrees, the second is 60 and the third is 30. They handle the valve seat with ease and effortlessness.
After the saddles have been processed with cones, they need to be ground in. What tool is used to grind the valves, I recommend reading the article (Tool for grinding valves).
Perhaps this is all from a special tool, then everything can be done with the help of keys and screwdrivers.
At the moment this is all, and if something else appears, I will definitely add it.
So I decided to make a simple stand for repairing an engine with my own hands: blueprints , photo and description of the device are attached.
The stand was made from a profile pipe 70 x 70 mm (wall thickness 3 mm), it took about 3 meters.
I cut the blanks, so that the structure turned out to be collapsible, I made a bracket from a 4 mm corner and reinforced it with kerchiefs.
I made 3 holes in the profile with a grinder, and inserted bushings from the piston pins from the VAZ engine and welded.
From a piece of metal 6 mm thick I made a bracket for a VAZ engine, for another engine you need to make your own bracket.
Then I welded a piece of pipe to the stand, drilled 4 holes for fixing, at an angle of 90 degrees in the swivel pipe, and one on the stationary one, and 2 holes for the handle.
The stand has successfully passed the tests.
From the profile I welded the legs, primed the structure.
Surely every car owner has heard about engine repair stands. Below we will consider what it is, what characteristics does such a device have, and, of course, is a home-made option suitable?
Of course, we all want our vehicle to serve us for a long time and at the same time to be in excellent working order all the time. However, this only happens in fairy tales, and in practice even new cars taken from brand showrooms need to be repaired within a few years. And what can we say when the owner does not spare his "iron horse"? In general, many factors contribute to the failure or incorrect operation of one of the main parts of an auto - engine.
So, let's look at the main mistakes that lead to such dire consequences. As already mentioned, incorrect operation of the vehicle is reflected in the most negative way, for example, the use of unsuitable fuel or low-quality technical fluids. Untimely oil and timing belt change, constant overload of the car will also negatively affect. Even disastrous will be the neglect of the engine's need for warming up in the cold season. And what can we say about malfunctions after mechanical impact due to an accident?
VIDEO It is not so important why the unit failed, in any case, the result is the same - the need for diagnostics and further repair work. In this case, a special stand used for such purposes will be indispensable. A suspended motor is attached to it, and then it becomes much easier to diagnose, transport and repair the unit. In addition, most of these mechanisms are equipped with a special unit, thanks to which the angle of rotation of the engine can be changed in any range, which greatly facilitates the work carried out.
But, like all fixtures, such a stand also needs good care. Therefore, be sure to carry out a visual inspection to search for defects, and if there are any, then the operation should be postponed. Before each use, check whether all fasteners are securely fixed, if not, then make a constriction. And of course, keep it only in a dry and clean place, remove all debris after each use, and lubricate all moving parts regularly. Only with proper operation, the stand, even a homemade one, will serve for a long time, reliably and will pay off if you are going to become a minder.
VIDEO
So, working with such stands is quite simple, but do not forget about safety precautions. At this point, we will pay attention to how to properly operate such devices. It is strictly forbidden to exceed the permissible tonnage, otherwise the structure may not withstand overloads, and the engine will fall ... The consequences of such a situation can be very different, and the least is damage to expensive equipment. In addition, pay enough attention to the choice of the surface on which this object will be located, it must be flat and, of course, capable of withstanding significant loads.
The next criterion is the installation of the load. Before repairs, the engine must be securely fixed strictly in the center, while acting with extreme caution and accuracy. Remember, even your life can depend on the reliability of the fastening. And, of course, if you purchased such a stand in a store, then you do not need to make any adjustments to its design, trust the professional developers.
VIDEO
We figured out the purpose, care and operation of this device, and, as you can see, it is an indispensable attribute especially for beginners and professional minders. But it has one rather serious drawback - it is high cost, so not everyone will be able to immediately give a tidy sum. And if, in addition, you are not confident in your abilities and then abandon self-repair, then as a result, there is a high probability of being the loser. So let's look at how to design a homemade stand used to repair engines.
So, if you are going to make a living with this, and not just maintain only your car, then you should make the stand universal. After all, for example, for the engine of domestic cars VAZ ordinary flange fasteners to the rear are enough, but the engine from Bmw you can't fix it like that. Therefore, it is necessary to weld a pair of channels with ten-millimeter holes with a pitch of 50 mm to the rotating plate, and the latter should be located in the area of the motor mountings. But in order for the part to rotate quite easily around its own axis, its center of gravity must be strictly opposite the axis of rotation of the aforementioned plate.
Thanks to the holes on the channels, it becomes possible to mount motors of various sizes through adapter brackets.
The use of a manual hoist, which moves on beams, makes it possible not to construct a lifting mechanism above the stand, it is enough just to install it on the wheels, of course, they must be quite powerful. So it will be possible to simply roll the defective part to any place, and if this unit is not used, then it is also very easy to remove it to the far corner.
Quite often, repair work also involves flushing the engine, and keep in mind that this unit accumulates an incredible amount of dirt, and, naturally, in order not to deliver it across the garage floor, a pallet should be placed at the bottom of the stand. In this case, a fine mesh should be put on top of it, because the strong pressure of the jet can knock some small part off the engine and it will be much easier to detect it on the mesh than at the bottom of the pallet. In addition, you can put the elements of the disassembled unit on it and rinse them.
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Weekend design.
I rented a stand for repairs, but I had to give it away, the owner needed it. Urgently made myself the same. Costs / expenses: 900 rubles for a square tube 60x60, electrodes, a circle for a grinder. I will fasten the wheels after painting. The last picture is the original.
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City: Yaroslavl
Name: Alexey.
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Bolts - master-master 🙂 As it is more convenient, I like welding more.
If you make the stand higher, then you can put spacers on the outer legs.
Bolts - master-master As it is more convenient, I like welding more.
If you make the stand higher, then you can put spacers on the outer legs.
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So at least a painted stand, then?
I wish the motor and the stand a greater MTO!
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I didn’t paint, I don’t have a repair trowel to attract clients with beauty
Engine from Porsche 924, remanufactured.
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Fastened to the gearbox bell mounting holes. So as not to interfere with the flywheel, there are spacer tubes.
Square plate - a piece of channel 12 mm thick, racks for mounting the engine - a square bar 20x20. Hardened bolts from some kind of car, bought in auto parts. The grooves in the slab were first drilled at the ends, the middle was cut out with a grinder (this is faster than milling). To the lower frame, the corner is vert. the stand is attached with 4 bolts, as on the original.
The design is repeatable at home without any major equipment. Welding and grinder
Manual cylinder head repair machine
SPECIFICATIONS: Range of machined saddles, diameter (optional - any) from 25 to 50 mm
Machine for repairing the head of the block (straightening the saddles, replacing the saddles)
BASIC EQUIPMENT: Universal table, 1 kt .:
bracket with a vertical stand f27x600 and a crossbar f44x580;
adjustable parallel brackets;
parallels for head installation;
pressure plate for fixing the head. Electromagnetic device, 1 kt .:
an electromagnet with a vertical post, a handle and a switch;
body of the feed and cutting mechanism;
spindle micro-feed bushing and nut;
The next aspect of cylinder head modification that you should pay attention to is turbulence.(swirl ) or in the case of 4 valves per cylinderTumble .
Typically, the swirl is created by moving the channel away from the center of the valve. Any bend in the channel resulting in the correct twist is welcome (channel on the left side) The bored channel (on the right side) shows a common mistake many tuners make in filming metal in a more convenient location. Channel straightening, leading to a decrease in turbulence, causes poor mixture formation, combustion process ..., with all the ensuing consequences
The design (design) of the Semi-hemi (Lotus Twin Cam) or 4 valves per cylinder pent-roof cylinder head (discussed as an example in Cylinder Head Tuning Part 2) is usually very good, little can be done there. The combustion chamber sometimes needs light work, mainly if a larger valve is to be used. The main condition is to keep your boring, grinding tool away from the channels. The maximum that can be done is to remove cast irregularities, bumps and everything if you do not have a blowing stand. What needs to be done and how was described in the previous post, working with the valve seat and the area just below it, in the throat of the channel. High blowdown rates, fillability (CFM) should be achieved through optimization, and not by increasing the size of the flow area of the channel.If you simply increase the size of the channel, the flow rate will decrease, this in turn will reduce the ramming process, the Camshaft part 1 wrote about this) and the flow reversion will increase. The result is deterioration at low and medium revs and even (often) possibly without benefit, gain at high revs.
To be honest, it is always difficult and expensive to get a significant increase in power from a well-designed headstock. If you have a blowdown stand, a swirl meter and an unsuccessful design of the cylinder head channels, you must adhere to the following logic for"Improvement"
This is what the inlet channel looks like in section, on it the dotted line (this is only a principle) indicates the places for the completion (optimization) of the channel
Straightening the channel is a good idea, our goal is to increase the bend radius at the top and bottom, but on the upper, long bend of the channel, we usually cannot remove much metal due to the close location of the valve spring seat. Typically, the short, underside of the duct is the number 1 obstacle to good blowdown results at medium to maximum valve lift. Formula 1 engines have a very large bottom bend radius. The underside is modified by the application of additional epoxy or aluminum material, thereby increasing the radius and improving the flow direction into the combustion chamber.
The added material to the bottom bend will significantly reduce the flow area. To compensate, it is necessary to smoothly expand the channel in this place, thereby it will no longer be round, but oval. A typical, round 30 mm in diameter inlet will taper down to 23 mm and widen to the sides up to 36 mm. If this is a cylinder head with 4 valves per cylinder or Hemi, in this case, we do it according to the following principle.
If these are 2 valves per cylinder, then to improve the vortex we expand the channel on one side
And the last thing for today, it is worth talking about the increase in channels and especially about the minimum flow area, usually it is located immediately under the throat of the channel (maybe in another place). If you have a modern engine with a good pent-roof cylinder head (like a duratek engine), don't touch it, don't increase it - unless you're building a racing engine. An increase will lead to a significant deterioration in the power performance in general. Of course, if you are building for certain tasks, you have decided on the working range, maximum revolutions, then only in this case, open the channel, but not more than the task at hand requires. This is not a problem, by increasing the size of the channels, you will naturally increase the maximum values of the air flow, but at the same time you will lose the bottom and middle.
Let's take a look at the comparison test conducted by David Vizard with a 383 Small-Block (6.27 liter) engine. Here you can clearly see how the torque curve changes with increasing channels and this is on 383 Smal block.
Video (click to play).
In the next post I plan to talk a little about the revision of the combustion chamber, about the compression and displacement zones (Squesh Area), and about the valve space (Valve shrouding).
