The "Uralovsky" opposition is said to have little power and a lot of noise. I was most annoyed by the noise. There was a case, not with me. Foreign guys came to go for a motorcycle ride in Russia, all like one in foreign cars. Warming up motorcycles, waiting for the "Ural" escort to start. At last I earned - and silenced all "bourgeois" motorcycles with my noise.
It wasn't the roar of the exhaust - the rumble and clanking of the engine. The guests were amazed: they said they saw and heard a lot of things in the world, but to do so! Guilty of this outrage - the gears of the drive and the generator. The reason is not so much the poor quality of the gears themselves (it is quite acceptable), but that there are gaps between them. First, the cam of the spreader cam is pushed through the pushers, rods and rocker arms to compress the valve spring - with one side of the teeth loaded. And when the top of the cam is passed, the force of the compressed spring tries to turn the camshaft further, loading the other side of the teeth. At the time of passing through the cam tip, the load is transferred from one side of the tooth to the other. That's what we hear.
Here is what is located under the chain drive:
- 1 - oil is supplied to the front journals of the camshaft through a plastic tube;
- 2 - a plate that holds the crankshaft from axial movement.
The engine has sprockets instead of three ever-warring camshaft drive and generator gears. The drive became a chain drive. No more voyeurs.
You can't get rid of the gaps: aluminum alloy, from which the crankcase is cast, heating up when the engine is running, expands quite a lot, the distance between the axes of the crankshaft, camshaft and generator increases - so expands the gaps. If you try to reduce them, then on a cold engine gears will bend the teeth into each other - then and to break near. The only thing you can do is try to reduce the noise by adjusting the position of the generator. But don't expect any special results.
Shall I make the drive of the camshaft by belt, as with VAZ-2108 engines? It is a silent variant in general, but the volume of alterations scared me, and I refused it at once. And where to get a belt of a suitable length! And if to apply chain gear (by the way, BMW designers on their opponents also went this way)? After all, the chain is easy to rivet to the right size.
I used the details of the timing and chain from "Moskvich". At once - a question: where to get a star for a drive of the generator? I found the right one on the chain tensioner all the same "Moskvich". To all stars that they "sat down" on the "Irbit" shafts, welded transition bushings. Since the distance between the shafts is small, the "branches" of the chain turned out to be short, and therefore, the tensioners and soothies are not needed for it.
This redesign caused quite serious changes in all engine components - because the camshaft now rotated in the opposite direction, and not only depends on it the operation of the valve mechanism. The gear in its back part drives the oil pump, and on the front end of the camshaft is the rotor of the ignition system and the drive of the breather valve spool. The biggest problem is the redesign of the camshaft itself. The part was cut in the middle on the lathe and the steel bushing was inserted into the cut. He turned one pair of cams relative to the other by 120°, and the joint was welded by argon welding. After heating the part, of course, "led", but to rihtovat calendar, and therefore, the fragile part of the hammer did not dare - the risk of breaking it too great. It was tricky: in the area of the joint he made a small point of electric welding - and the part immediately bent a little bit. And so on until the shaft beat almost disappeared. On the first variant of the motor the height of the cam increased by 4 mm. In the new engine it was distributed as a standard one. Experience has shown that large valves and rocker arms with a changed ratio of the shoulders of the heads from the "Wolf" (and the engine is installed on them) provide quite sufficient passage cross-sections. Besides, the enlarged cams can work only with "Dnepr" pushers. The same engine has "Irbit" ones. In order to use the "Starooskol" ignition system with the changed direction of rotation of the rotor sitting on the camshaft, the transmitter's wires were exchanged. The only thing I had to do was to adjust the ignition advance angle. For this purpose, the rotor had to be cut under the pin, and during the finishing process the holes for the sensor plate bolts had to be moved as well.
The drive of the breather plug also had minimal modifications: in the glass itself it made a new cut for the pinion pin of the camshaft.
The most important part of the work is the modernization of the lubrication system. The main bearings used in this motor are plain bearings (instead of "native" ball bearings), and it is not enough for them to simply spray the oil on which the entire lubrication system of the "Urals" is based - they require stable oil pressure. The "Dnieper" oil pump has a much higher capacity - and it was installed. But after the drive was rebuilt, the pump gears began to rotate in the other direction, i.e. they were practically swapped in and out. As a result, I removed the standard by-pass valve of the oil pump and replaced it with an oil intake. The oil enters the engine through a tube from the other side of the pump.
Continued in the next part...
https://zen.yandex.ru/media/id/5d92c71fe6e8ef00b15bb4a2/a-liter-for-the-urals-motor-repair-resulted-in-alterations-part-2-5d957a66a3f6e400ada03725